The problem with the file "handler" in php

Faced the following problem, information from the form is not entered into the database, but if I remove the id = "datepicker" from the line

<input name = "datepicker" type="text" id="datepicker" value="" /> 

Everything starts to work right away (but id = "datepicker" needs a calendar from JQuery to work)

Form Code:

  <form action="reserve_room_process.php" method="post"> <input name="user_id" type="hidden" value="<?php echo $_SESSION["username"];?>" /> <input name="name" type="hidden" value="<?php echo $nameOfUser; ?>" /> <input name="room" type="hidden" value="1" /> <p>Choose time for meeting room: <input name = "datepicker" type="text" id="datepicker" value="" /> <select name="time"> <option value="9">9:00</option>; <option value="10">10:00</option>; <option value="11">11:00</option>; <option value="12">12:00</option>; <option value="13">13:00</option>; <option value="14">14:00</option>; <option value="15">15:00</option>; <option value="16">16:00</option>; <option value="17">17:00</option>; <option value="14">18:00</option>; <option value="14">19:00</option>; </select> </p> <input type="submit" name="submit" value="Reserve" /> <br /><br /> <!-- <a href="manage_content.php">Cancel</a>--> </table> </form> 

Handler Code:

 if(isset($_POST['submit'])){ $user_id = $_POST["user_id"]; $name = $_POST["name"]; $time = (int) $_POST["time"]; $date = $_POST["datepicker"]; $room = $_POST["room"]; $visible = 0 ; $currentTime = (int)date('H'); $query = "INSERT INTO room_reserv (user_id , name , rtime , rdate, room) VALUES ('{$user_id}' , '{$name}' ,'{$time}' , '{$date}', '{$room}') "; $result = mysqli_query($connection, $query) or die(mysqli_error($connection)); redirect_to("discussion.php"); }