what if you have multiples (smith,john; smith, albert)?
Maybe post the new problem version? First, I'd check in the immediate window what the combo value is at runtime based on the sql that was working; maybe it's not what you think. If it looks OK, you could dump the sql that the form is based on into a new test query to see the resulting record(s) based on that combo value. Don't forget to factor in the LIKE operator. The form recordsource might be conducive to returning a value(s) other than what you think it should.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.