Why the application crashes when switching to fragment?

Attached are two fragments. The second is identical in structure to the first. Called from the menu drover. The first and second open without problems. But as soon as I add a button click handler in the second when opening a fragment with this button, the application crashes. Fragment code: public class FragmentTanks extends Fragment {

private OnFragmentInteractionListener mListener; public static final double pi = 3.1415926535; Animation anim_show; Animation anim_hide; //Раздел объявления Layout //**************************************** LinearLayout L_tanks_flow_wash; LinearLayout L_tanks_volume_solution; //Раздел объявления Button //**************************************** Button btn_tanks_flow_wash; Button btn_tanks_flow_wash_calculate; Button btn_tanksF_volume_solution; Button L_tanks_volume_solution_calculate; // Раздел объявления EditText и Spinner //**************************************** EditText et_tanksF_diameter; EditText et_tanks_angle_spray; EditText et_tanks_current_flow; Spinner sp_tanks_pollution_level; EditText et_tanks_estimated_flow; EditText et_tanksV_diameter; EditText et_tanks_cone_height; EditText et_tanks_cylinder_height; EditText et_tanks_volume_solution; public FragmentTanks() { } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_tanks, container, false); anim_show = AnimationUtils.loadAnimation(getActivity().getApplicationContext(), R.anim.anim_show); anim_hide = AnimationUtils.loadAnimation(getActivity().getApplicationContext(), R.anim.anim_hide); //region Поток на мойку танка //Раздел инициализации Layout //**************************************** L_tanks_flow_wash = (LinearLayout) rootView.findViewById(R.id.L_tanks_flow_wash); // Раздел инициализации Button //**************************************** btn_tanks_flow_wash = (Button) rootView.findViewById(R.id.btn_tanks_flow_wash); btn_tanks_flow_wash_calculate = (Button) rootView.findViewById(R.id.btn_pipes_flowD_calculate); // Раздел инициализации EditText и Spinner //**************************************** et_tanksF_diameter = (EditText) rootView.findViewById(R.id.et_tanksF_diameter); et_tanks_angle_spray = (EditText) rootView.findViewById(R.id.et_tanks_angle_spray); et_tanks_current_flow = (EditText) rootView.findViewById(R.id.et_tanks_current_flow); sp_tanks_pollution_level = (Spinner) rootView.findViewById(R.id.sp_tanks_pollution_level); et_tanks_estimated_flow = (EditText) rootView.findViewById(R.id.et_tanks_estimated_flow); btn_tanks_flow_wash.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { if (btn_tanks_flow_wash.getVisibility() == View.VISIBLE) { hide(L_tanks_flow_wash); } else { show(L_tanks_flow_wash); } } }); btn_tanks_flow_wash_calculate.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Toast.makeText(getActivity(), "Норм!", Toast.LENGTH_LONG).show(); } }); //endregion return rootView; } 

}

Fragment markup:

 <?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="fill_parent" android:layout_height="fill_parent" tools:context="ru.zets_swe.calculator.fragments.FragmentTanks"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:padding="6dp"> <Button android:id="@+id/btn_tanks_flow_wash" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/tv_tanks_the_flow_to_the_sink_tanks" /> <LinearLayout android:id="@+id/L_tanks_flow_wash" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:visibility="visible"> <TableLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:baselineAligned="false" android:shrinkColumns="0" android:stretchColumns="*" android:textAlignment="center"> <TableRow android:layout_width="match_parent" android:layout_height="wrap_content" android:textAlignment="center"> <TextView style="@style/table_text" android:text="@string/tv_tanks_diameter" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_angle_spray" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_current_flow" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_pollution_level" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_estimated_flow" /> </TableRow> <TableRow android:layout_width="match_parent" android:layout_height="wrap_content"> <EditText android:id="@+id/et_tanksF_diameter" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:ems="1" android:hint="0" android:inputType="number|numberDecimal" /> <EditText android:id="@+id/et_tanks_angle_spray" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:ems="1" android:hint="0" android:inputType="number|numberDecimal" /> <EditText android:id="@+id/et_tanks_current_flow" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:ems="1" android:hint="0" android:inputType="number|numberDecimal" /> <!-- <EditText android:id="@+id/et_tanks_pollution_level" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:editable="true" android:ems="1" android:enabled="false" android:inputType="number" />--> <Spinner android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/sp_tanks_pollution_level" android:layout_gravity="center_horizontal" /> <EditText android:id="@+id/et_tanks_estimated_flow" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:editable="true" android:ems="1" android:enabled="false" android:inputType="number" /> </TableRow> </TableLayout> <Button android:id="@+id/btn_tanks_flow_wash_calculate" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:background="@color/colorAccent" android:text="@string/btn_text_calculate" /> </LinearLayout> <Button android:id="@+id/btn_tanksF_volume_solution" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/tv_tanks_volume_of_the_solution_in_the_tank" /> <LinearLayout android:id="@+id/L_tanks_volume_solution" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:visibility="gone"> <TableLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:baselineAligned="false" android:shrinkColumns="0" android:stretchColumns="*" android:textAlignment="center"> <TableRow android:layout_width="match_parent" android:layout_height="wrap_content" android:textAlignment="center"> <TextView style="@style/table_text" android:text="@string/tv_tanks_diameter" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_cone_height" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_cylinder_height" /> <TextView style="@style/table_text" android:text="@string/tv_tanks_volume_solution" /> </TableRow> <TableRow android:layout_width="match_parent" android:layout_height="wrap_content"> <EditText android:id="@+id/et_tanksV_diameter" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:ems="1" android:hint="0" android:inputType="number|numberDecimal" /> <EditText android:id="@+id/et_tanks_cone_height" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:ems="1" android:hint="0" android:inputType="number|numberDecimal" /> <EditText android:id="@+id/et_tanks_cylinder_height" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:ems="1" android:hint="0" android:inputType="number|numberDecimal" /> <EditText android:id="@+id/et_tanks_volume_solution" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:editable="true" android:ems="1" android:enabled="false" android:inputType="number" /> </TableRow> </TableLayout> <Button android:id="@+id/L_tanks_volume_solution_calculate" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" android:background="@color/colorAccent" android:text="@string/btn_text_calculate" /> </LinearLayout> </LinearLayout> </ScrollView> 

If you remove btn_tanks_flow_wash_calculate, then everything works. Where could the problem be?