How do I write the FileName to show 'Name ' + DespatchFrom
+ '-' + DespatchTo
as FileName
Those values are parameters but I keep getting validation errors.
I have also tried 'Name ' + DateAdd(DateInterval.Day, 1-WeekDay(Today), Today())
as FileName
Unless your date fields are in already a text field, you'll need to convert them otherwise you'll get a conversion error.
The Data Driven query needs SQL syntax which is why your second attempt with TODAY failed.
I think you want something like