Head disappears when walking

Hello!
I have a walking character with a standing profile and left and right profile. The character walks perfectly to the left, (except the head is a bit too high). But when walking to the right, the head disappears, completely.  As far as I can see the right profile is tagged the same was as the left profile. Has anyone got any ideas what I'm doing wrong? 

All the best 
Elina Tyskling