I've been looking at this too and it's been driving me a little scatty whilst waiting for help on another issue.... however (and I may be wrong) I seem to remember my ex boss telling me something about the first line of lookups and beware with them, so whilst I can't be of much help I think it may be an "excel" thing. I think that's why he always left the first line of his spreadsheets empty....

I have tried playing around with your attachment, but I couldn;t get the thing to work yet.