执行存储过程，第一遍可以，第二遍出错

系统提示
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Debugger Exception Notification
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Project Re.exe raised exception class EAccessViolation with message 'Access violation at address 4DD419E8 in module 'msado15.dll'. Read of address 00000000'. Process stopped. Use Step or Run to continue.
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SP_Percent.ExecProc;//第二遍，在这个地方就出错
procedure TFrm_RP.Btn_AppPercentClick(Sender: TObject);
var
  Str_Path,Str_RPFile:string;
  Str_DeptName:string;
begin
  inherited;
      try
            try                  with DM do
                  begin                      SP_Percent.Close;                                     //通过存储过程来调用
                      SP_Percent.ProcedureName :='P_AppointPercent';
                      SP_Percent.Parameters.Clear;
                      SP_Percent.Parameters.Refresh;
                      SP_Percent.Parameters.ParamByName('@S_BeginTime').Value := DTP_Begin.Date;
                      SP_Percent.Parameters.ParamByName('@S_EndTime').Value := DTP_End.Date;
                      SP_Percent.Parameters.ParamByName('@DeptID').Value := '25';
                      SP_Percent.Parameters.ParamByName('@AllDept').Value := 1;
                      SP_Percent.Parameters.ParamByName('@CountApp').Value := -1;
                      SP_Percent.Parameters.ParamByName('@CountAppYse').Value := -1;
                      SP_Percent.Parameters.ParamByName('@CountAppNo').Value := -1;
                      SP_Percent.ExecProc;//第二遍，在这个地方就出错                      Str_Path:=  ExtractFilePath( Application.ExeName );
                      Str_RPFile := Str_Path + 'rp\AppPercent.rmf';
                      RMDBDataSet_DM.DataSet := SP_Percent;
                      RMReport_DM.LoadFromFile(Str_RPFile);                      RMReport_DM.PrepareReport();
                      RMReport_DM.ShowReport;
                  end;            except
                  on E:Exception do
                  begin
                        Write_LogErr(FinalUnit+'0004:打印赴约图表',IntToStr(E.HelpContext)+':'+E.Message,'');
                  end;
            end;//end except      finally
            DM.SP_Percent.Close;
      end;//end finallyend;