Yes, either try a different one, or keep your tips close together. That doesn't mean casting on only on the tips, that will be too tight. And just practice, maybe on some leftover yarn.
Oh, if you're doing the LT cast on, try the 'thumb' variation which uses both hands. I never could get the regular one and discovered the thumb method myself. I've tried doing a regular one now and am more successful, but after a few sts the thumb yarn needs to be pulled up and it becomes uneven. But I can always do an even CO no matter how many sts with the 2 hands version.