Ошибка: Access Violation при создании MDIChild формы в dll XE7

procedure TDocForm.ToolButton5Click(Sender: TObject);
var
   PrepareTickets:procedure(MainApp:HWND;ConObj:_Connection;idDoc:Integer);cdecl;
begin
   Tickets := LoadLibrary('TicketsProject.dll');
   if Tickets = 0 then
   begin
      MessageDlg('Неудалось загрузить библиотеку TicketsProject.dll.',mtInformation,[mbOk],0);
      Exit;
   end;
   @PrepareTickets:=nil;
   @PrepareTickets:=GetProcAddress(Tickets,'PrepareTickets');
 
   if (@PrepareTickets = nil) then
   begin
      MessageDlg('Не найдена искомая процедура!',mtInformation,[mbOK],0);
      FreeLibrary(Tickets);
   end
   else
   begin
      PrepareTickets(Application.Handle,Connection.ConnectionObject,DataSet.FieldByName('idDoc').Value);
   end;
end;

var
  DllAppHandle:HWND;
 
{$R *.res}
 
procedure PrepareTickets(MainApp:HWND;ConObj:_Connection;idDoc:Integer);cdecl;
begin
   DllAppHandle := Application.Handle;
   Application.Handle := MainApp;
   fTickets := TfTickets.Create(Application.MainForm);
   LockWindowUpdate(Application.Handle);
end;
 
procedure MyDllProc(Reason: Integer);
begin
   if Reason = DLL_PROCESS_DETACH then
   begin
      if DllAppHandle<>0 then
         Application.Handle := DllAppHandle;
   end;
end;
 
exports
   PrepareTickets;
 
begin
   DllProc:=@MyDllProc;
end.

DllAppHandle := Application.Handle;

Application.Handle := MainApp;

Application.Handle := DllAppHandle;