Searching Leads by Partner Function

Greetings!

I am attempting to search for Leads by the criterion "Partner Function". When the results come back, it displays Leads where the specific function is not being used in addition to the ones where the function is being used. It doesn't seem to matter where the function is a custom function I created or not.

Example:

I have only one lead with partner function of "Key Account Manager". When I search leads with that criterion...it returns 79 leads. meaning there are 78 leads which do not have that function, but are in the results list.

Anyone have a clue why it might be happening? And what I can do to "fix"?

Thanks for any help.

Jim