Sumproduct & Len Function

Can someone help me with why this formula is returning a #NA?

=IF(SUMPRODUCT((Revisions!$C$3:$C$410=$B5)*(LEN(Revisions!$F$3:$F$411)=0)),"Y","")


Essentially what I'm trying to do is look at the Revisions tab, and if at any spot where column C (Revisions Tab) has the same contract number as $B5, and all cells in "F" (Revisions Tab), marked with a "Y", then it would say "Yes" - meaning we have received all revisions. If there is a blank value in column F, or a "N", it would say "No". Indicating not all revisions are returned.

Sorry, I'm still confused. I'm not sure exactly what I want formula wise as I can't get the current function to do what I'm trying. Essentially on the revisions tab, we enter a contract number, then 1, 2, 3, 4, etc for the number of changes to the contract. When the Revision is signed, I mark a "Y" column F of the revisions tab. If anywhere on the Revisions tab, where Column C is equal to contract value in Column B (Master Tab), and column "F", does not have a "Y", then it would say "NO". If anywhere where the contract value is found and they are all marked "Y", then it would say "Yes". Does that make sense? Sort of confusing to explain.

Cell AY is holding the Formula in the "Master" Tab.

Master Tab:
B4:B120 - This holds individual contract numbers
AY4:AY120 - this is the cells holding the formula seeing if all revisions are collected.

Revisions Tab:
C4:C300 - These cells are the contract numbers. Each revision (can be many to a contract) is listed as a seperate line. The contract # is always listed in column C.
F4:F300 - This listed a "Y", "N", or Blank, which is indicating if we have received the revision back. N and blank mean the samething, not returned.

Basically if any line in the revisions tab has the same contract number as the row we are looking at on Masters, and has a "N", or Blank Space, then it would return a "NO" - indicating not all revisions with that contract number are marked with a "Y".