I have the following nested IF statement and cannot get it to fully cooperate. I believe something is wrong with the way I nested the IF statements. Any help is appreciated. Thanks in advance.

=IF(D11=VLOOKUP(D11,LAB!$A$7:$A$1329, 1, FALSE), "LAB", IF(D11=VLOOKUP(D11,LAB!$AI$1291:$AI$1337, 1, FALSE), "LAB", IF(D11=VLOOKUP(D11,Model!$B$40:$B$136, 1, FALSE), "RVU", "Other")))