Cast Credit

Hey, 

I have been trying to add one of my cast on the cast credit and having a problem doing that, and now it is finally up there, but it is showing he is only in one of the episodes, which is different than what others are listed as. I have been trying to correct it, but once I enter the pages, he is not listed in the cast list, which I am unable to correct or delete. Any ideas on how to solve that? 

Thank you