Well are you sure it is a dual jack, input/output? It should be marked to say, otherwise you can check your manual.
However, even if it is a dual one, that doesn't mean it will work with all headsets. Sadly some just don't work as they should.
A way around it, other than replacing the jack itself, would be to get a 3.5mm to USB adapter (can usually find online for less than $10) and connect that way.