Excel

Can somebody help me on this one as soon as possible.
I have two workbooks, one is current bom operations, having 3 columns A(item no, B(operation no) & C with 50,000 rows and another is optext having 4 coloums (A (item no),B(operation no, C& D) with 25,000 rows. What I want to do is match A and B coloumn in current bom file with A and B column in Optext file, if item no in Amatch with B and is same as optext file and current boom file then text appears in D colum in current bom. I tried to put this formula, can any body tell me what I am doing wrong here, or is there any other way we can do this.
=IF(AND(A2=[OPTextQSTEST1.xls]Sheet1!A2),B2=[OPTextQSTEST1.xls]Sheet1!B2), D2"")
bascially I was trying to link the formula between two workbook, may be I am doing something wron with the formula.

You’ll need either to use either Hlookup, or Vlookup - (most likely, just Vlookup).
The file to which the match/vlookup command refer to (file B) will need to be sorted by the reference column(s), When sorting, ensure that you select ALL data columns (not just the one to sort by), otherwise all your info will be all mucked up.

Microsoft have an example here:
http://technet.microsoft.com/en-us/library/cc750573.aspx