Can you post the code you're using for your search? Specifically the part where it calls on the combo box itself. Also, post the sql you're using for the combo's rowsource. You are probably bound to that table's primary key, but on the combo control, you're displaying a different field. So the combo's .Value property is going to be the selected index number of the table.
So the value you visually select (the unbound data), may not be the value that's being passed to your search function.
If this is the case, you can try using the column feature to get the currently selected unbound data.
me.cboObject.Column([Column # starting with 0],[Row #])
In this example, the first number (1) is the second column #, and the Listindex property provides the currently selected row #.
me.cboObject.Column(1, me.cboObject.ListIndex)
There might be a property that just returns what the selected visible text is, but I cant remember what it is offhand.