Adding a Task to a Project.

Hi,

I have a User who is trying to add a new task to an existing Project but keeps getting the following error message - 'You have charged a supplier invoice on this task with a finish date that is after the task finish date'.  Have checked the 'Expenditure Enquiry' and all the dates entered are within the dates of the Project/Tasks.  Also amended the tasks start date and finish date to the project start and finish date but continue to get the error message.

Any ideas what might be causing this??

Thanks