VLOOKUP not working correctly

I have attached my workbook, because this issue is a little hard to explain.
On the Search sheet I have several vlookup formulas which return records based on the search criteria entered into the search cells at the top. When no search criteria is entered it correctly displays all 317 records on the Return Data sheet (from rows 11 to 327). The search is correctly displaying the records that meet the search criteria when criteria is added, however when any kind of search is performed it also displays the first record on the Return Data sheet in row 328 and below. How can I prevent this from happening? It seems I need to tell the code to do nothing when the record it is looking up is blank.

This is an example of the formula im using in one of the rows:
=IFERROR(VLOOKUP(INDIRECT("ReturnData!A"&ROW()-5),ReturnData!$B$6:$K$49969, 3, FALSE),"")

Thank you for your time,
James