Traktor pro 1.2 - filters

I'm trying to set up a low pass and hi-pass filter using a knob for each. But I can't figure out how to do this. I can make a knob into a filter, but the knob becomes both low pass and high pass i.e. it's neutral at the halfway point - this doesn't give the flexibilty or control I want.

I want one knob to start at 0 and gradually cut out the low frequences as I turn it up to 100. And the other knob to do the reverse.

I'm sure there is something quite simple I'm not doing - can someone point me in the right direction?

I didn't check but from memory if you set up a bank effect as an advanced one, choose "filter" and if you tick on the third button you'll get only the low pass filter.

Or set up the 'range' of the hp or lp settings to 0/50 or 50/100?

A quick thought really I'm quite new to Traktor too, but I guess that's one or the other way round.