HELP! my ferrets poop EVERYWHERE!!!?

I have several ferrets 2 of which Ive had since they were babies and 2 I got as adults. What I've learned with my ferrets is you have to constantly be on their little behinds while trying to train them NOT to poop everywhere. When you get them from a store they are in a cage where the do just go wherever and in the wild obviously there aren't little ferret reststops.. lol.. I kept mine in a ferret cage and kept the cage in a spot I would see it more often than not (in the living room). I found that corner litter boxes did me no good because they were just to small and they wouldn't use them. I went out and got cat size litter boxes and cat litter (non clumping, as the clumping kind is bad for your ferrets). I set the 2 boxes up on the bottom of the cage, 1 in each corner and then every single time I saw them starting to go somewhere that wasn't in the box I'de just lift up their and put it in the box. When I would see that they were using the boxes they would get treats. Then I would let them out to run around and adjust the ladder so they had a ramp to get in and out of the cage so they could use the litter box, if they went outside of the cage on the floor then play time was over and no treat. Eventually they got it.. You could also keep a seperate box outside of the cage so they can go there and don't have to keep going in and out of the cage. I have to do that with mine now because they are older. After they were litter trained I found putting carpet in the cage kept them from going places other than in the litter box also. I know you said you put cloth down on the floor and they still go but maybe that will change if you can get them to start going in the boxes. Make sure to keep the spots they use the bathroom (litter boxes) clean, ferrets are like cats where they don't like to go in a dirty box therefore they will go outside of the box. Every once in awhile you may still get a surprise.. Ferret training isn't always 100% fool proof.. Also when looking into treats for your ferrets please don't give them raisins, cereals, etc. there are sugars in these things and they are VERY bad for the long term health of your ferret. One of my ferrets was fed a VERY VERY bad diet by the person I got her from a few years ago and now Im afriad she suffers from Insulinoma where she gets seizures and such.