If you are not able to see any data for the VAT return then it is worth checking to make sure that the postings are in the correct period you can do this by selecting Posting Enquiry and searching for a transaction type or date.
Once you have located this select Details tab and check the period they are posted in.
You can also check in the Month End program to see what month you are currently in to make sure the correct periods are open.
If you have posted these incorrectly against the last periods that have already been submitted through VAT Management you will have to reverse these postings and put them back on in the correct month.