Error instead of warning? E1002 Symbol 'TThreadPriority' is specific to a platform

The code in delphi 10.1 berlin gives 3 identical errors. In other files for the 'TThreadPriority', the W1002 was the same but varning. OS win7 x32

[dcc32 Error] unit1.pas(80): E1002 Symbol 'TThreadPriority' is specific to a platform IServiceThread = interface( IUnknown ) [ _IID_IServiceThread ] function Get_Priority(): TThreadPriority; stdcall; procedure Set_Priority(value: TThreadPriority); stdcall; property Priority: TTHreadPriority read Get_Priority write Set_Priority; end; 

What kind of compiler option is needed in the module? or in the project settings? in the System.Classes file is defined as follows.

  {$IFDEF MSWINDOWS} TThreadPriority = (tpIdle, tpLowest, tpLower, tpNormal, tpHigher, tpHighest, tpTimeCritical) platform; {$ENDIF MSWINDOWS}