My initial hit would be to check the spelling and to make sure you have a seal up. Are you using Macaroon? I prefer to set up a 30 second spell rotation and use a /castsequence, since castrandom sometimes gets buggy, especially if you have a lot of commands. One issue I've noticed is that if you have two instant cast spells that would go through at the same time, only one gets through and the other is skipped, as though the UI thinks you used it when you didn't and never got abck a message saying cooldown is up.