=IF(AND($K$9=2,I17=3),"--",INDEX(A:A,MATCH(K17,D:D,0)))

This formula is returning the FALSE result when $K$9=2, I17=3 and therefore should return "--". The problem is with the "2" in $K$9 as I have changed $K$9 to a text symbol instead and the formula works. Is it something to do with being formatted as a number? I can't see why it would be because I17 is formatted as a number and is recognised fine. Thanks.

Dan