Complete Novice, having problems with adding stompboxes

So I'm a complete novice on my KPA, just started using it yesterday. I've figured out the Rig Manager and adding/removing rigs from my KPA, so that's gone ok. Now I'm trying to add stomps to whatever rig I'm playing a the time. I press slot A and choose a stomp - for example the green scream option. Whether I have it on or off, it sounds the same - completely clean tone. Changing the drive, tone, volume, and mix knobs makes no difference. What am I doing wrong? Thanks in advance!

That's the video I watched when I tried setting them up. Still the same result. The only difference I see from the video is every time I adjust the stompbox the "Quick" light right above the Browser setting on the left knob lights up. Any ideas?

No not really, they pretty much all sound clean to me.

Nevermind, I found it! I was going from the "direct output" to my Tech21 cab. I moved it to the "monitor output" and it's working. Now I feel really dumb.

Thanks Paul. Your question made me decide to check my wiring setup. I appreciate this forum and all of you experienced users that are willing to help us newbies find our way!