LR carts? Do you mean atomizers?
If you do mean atomizers, do you hear them fire? If so, they're fine.
With LR atomizers, they use a LOT more liquid. More than twice as much, in my experience. So you need to prime them quite a lot - don't be afraid to really get them wet. I had to prime my LR 901 with 10 drops just to get it going.
Also, you probably want to drip with them, rather than using carts. The filler in the cart doesn't give enough liquid to keep them wet.