I have a VLOOKUP problem...........

This formula doesn't work

=IF(B8<>"OVERHEAD","0","VLOOKUP(A2,Sheet1!A2:F1361,6")

Basically - if cell B8<>OVERHEAD - I want "0" and if B8="OVERHEAD" then perform the VLOOKUP

First part of formula works - I get zero 0 for non OVERHEAD values - however if the cell is "OVERHEAD" - formula returns VLOOKUP(A2,Sheet1!A2:F1361,6

How do I get this thing to work?

Thanks in advance..........