I hope you are filling the bowl with water before using it.
LOL. I posted a thread about this very topic a couple of years ago when I discovered this and had my thread deleted as people were too prudish to talk about poop. They even commented on my "childish" use of the word "poop", which was funny as my kids were toddlers and infants at the time so we talked about "poop" all the time!
Yes, there is a trick to pooping in an RV toilet. The trick is, as was mentioned, you have to fill the bowl with water first. That's why the toilet has to separate levers - one to allow water into the bowl and the second to open the flapper valve.
Steve