Index/Match assistance needed for search spreadsheet

This is the formula I'm using =INDEX(AF$3:AG$65536,MATCH(AB1,AF$3:AF$65536,0)+1+MATCH(A18,AF3:AG26))

The data used to search is in the "A" Column. The index information is AF: AG. AF is the match ie Car Rental in A13 should match Car Rental in AF column and then pull the COA# that matches Car Rental from the AG column and put into that cell. I keep getting either a N/A# or a REF# from the formula despite many changes. Test reference.xls


HELP!!! Thanks

Thanks.. This one worked too =INDEX($AE$3:$AF$26,MATCH(A18,$AF$3:$AF$26,FALSE),1)

Appreciate it, never fails as soon as I post I figure it out