I have some that miss the first time..I think they are over anxious to get their rat....

If it is an eyecap, wrap scotch tape around your finger (sticky side out) and GENTLY and CAREFULLY tap the snake on the eyecap....Do this only if you are sure that it is a retained eyecap, otherwise you could injure your snake's eye....if the eye cap is there, it should stick to the tape and come right off....Good luck and let us know what happens....