I'm no expert, but are you selecting pattern two before you assign it?, Hence I use Ezdrummer with FL and that's how I do it. So I simple click on the pattern no first, find a loop/rhythm, drag the pattern into FL channel, then another box appears and click OK. Sorry it's very vague, probably will be no help at all...lol

One of our members, 'Marino' is an expert, why not send him a PM, I think he's done a couple of video tutorials, youtube name is 'The Marino Experiment' or simply 'marino experiment', I'll try and give you a link later.

EDIT**

http://www.youtube.com/user/Marinoexperiment#p/a/u/2/64Sk6Nkuago

EDIT 2**
This is part one I think

http://www.youtube.com/user/Marinoexperiment#p/u/3/qrr8KGqgxAU