Practice it slowly, and have a plan for exactly how you're gonna do the trill. I think I do a triplet Eb-F-Eb but I'm not sure, I'm not at my piano right now. You do have to work it out slowly until you can do it reflexively.Can you explain in more detail what goes wrong with the trill?
Yeah, the trills can be difficult. I suggest rotating your forearm to assist with the trills. If you incorporate that along with your slow practicing, you should be able to play the trills in tempo with ease.