Forum:Oh My Papa problems...?

Hey, sorry if this problem has been mentioned, I had a look through the forum but couldn't find any solutions.

Basically, I have just killed Papa Khan, I sneaked out of his room undetected and returned the next day expecting Regis to be ready to make the NCR and Great Khan alliance. I spoke to Regis in his tent yet the only speech option I get is to say Goodbye? I have returned on later days to see if I needed to wait a while but still no luck. Has this happened to anyone else? I really don';t want to end the game without the Great Khans, I appreciate any help. Thanks.