Error in implicit conversion. Cannot convert null object. (Excel)

Hi, i try to write date table to my own excel template. On the other hand ı haven’t any trouble to write data table to new excel worksheet.

Exception:
RemoteException wrapping System.InvalidOperationException: Error in implicit conversion. Cannot convert null object.
at UiPath.Excel.Activities.WorkbookActivity`1.EndExecute(AsyncCodeActivityContext context, IAsyncResult result)
at System.Activities.AsyncCodeActivity.System.Activities.IAsyncCodeActivity.FinishExecution(AsyncCodeActivityContext context, IAsyncResult result)
at System.Activities.AsyncCodeActivity.CompleteAsyncCodeActivityData.CompleteAsyncCodeActivityWorkItem.Execute(ActivityExecutor executor, BookmarkManager bookmarkManager)

can you share your flow