Hi,
I really don't know,,but go to your List of People and see if you have him listed twice.
I had a similar problem and it was because I had the peron listed twice...Once as the son of his parents,,,,,then again as the husband/father,,,,and they weren't joined up.
On one of his names I could see his parents and line backwards. On the other name of his I could see his wife/children and family down to now.
Good
LuckKellie