I have some rebel brand pop-r's and they don't seem to work right for me.  They don't pop, they just go underwater when you try to give them a pop.  I have some XPS poppers and they work fine.  I just wonder if theres something I dont know about the rebel poppers.  

try popping them with your rod tip pointed towards the sky.

don't jerk as hard

(no pun intended)

Rebels have a longer lower lip that pulls the bait down. To get better action out of it you will have to sand the lip down like this one.

Like Randall said, sand the lower lip down.

I can usually pop them pretty good without sanding the lower lip, try shorter pops, less of a sweeping motion, which could be why it goes underwater.

I just bought one of these lures and caught two 5 lbs-ers this morning.  They didn't seem to mind that the lure goes under when popped.

But then I lost the pop-r to a turtle... :sigh:

I buy Pop-R's just to sand the lips down on them. They make them so much more versatile. You can walk, twitch, pop, chug, dart, dive, spit, etc. The more you tinker with the amount of lip you sand the more you find you can do with them  

what BassAkwards said is true, If pop-r's a lot and that seams to be the best and ezest way to pop them!

Also, make sure you're not using flourocarbon line. If you are, the line will sink, and as you pop the lure, the line will pull the bait downward instead of forward.

I too sand the lip down. But, I also sand down the whole bait until the walls and top of the bait are so thin that I can feel the bait caving in when I squeeze it. It works suprisingly well. According to zell rowland, It makes the bait sound more like a shad flicking on the surface.

Could be your line?  I've heard that if your line isn't to the size of your poppers they could upset the buoyancy.  I haven't had a problem with using fluorocarbon line with Rebel Pop-rs (teeny pop-rs are the shizzle!) the line weight I am using is 8 and 10lb test. With braided I am using 20lb at times.

Make sure your using mono and not fluorocarbon. Like everyone else said sand the lip down. Or.... you could buy some ricos or splash-its and avoid the problem all together (if you cool with dropping some $$$)