Numark Partymix 2 - Pads not working in Serato DJ Lite

I'm working in a music instrument store, and got handed a Numark PartyMix 2, that "did not work". Read about how it is supposed to work, downloaded Serato DJ Lite and found that it did in fact work.

Got updated on that the customer told us that pads did very little. Checked that, and found that customer was correct. Downloaded another DJ program (Mixxx), and there the pads worked like they should.

So it is something in DJ Lite that is wrong, but what? And how do I fix it?