Chony,
Without knowing in detail how you've been adding the DSP it's difficult to know what could be going wrong. As a starter though:
You need to be in the Style Effect page in mixing console. (Get there by pressing Direct Access followed by Style variation button D).
Highlight the DSP1 bar & press Type
Make sure DSP1 is selected in the Block Box.
Select a required Effect (in Category & Type boxes)
Press Parameter. This allows you to change things from defaults if you must, [but if you do you'll need to save them as a User Effect or they'll evaporate when you change Styles].
Suggest you keep with defaults at first.
Note at bott right there's the Effect Return level which can be altered if necessary. Suggest you leave it at default 64 at first.
Exit back (2 presses) to the Effect page.
Listen to the Style and turn up the DSP1 effect level (bott row) on the voice(s) required until satisfied.
Save it in a Reg. Bank.
It works for me
Often if applied to the rhythm section distortion effects (as well as the more usual compressor DSP's) can bring out all sorts of percussion nuances you may not have realised were there in the original style.
HTH John
[This message has been edited by jwyvern (edited 08-22-2007).]