I dono what was there to be upset or feel disappointed....
This invitation was for a function, and he was one of the invitees. And there are several other invitees who were also head of states. There was no joint statement with any of the guests.... I think we cannot ignore the fact that Modi was Prime Minister for few hours only and there was no official interaction with any of the departments. What ever knowledge he had was as a Prime ministerial candidate.
It is simple, When you go to a house as a guest the interactions and care would be good. You cannot expect the same when you go to the same house for a marriage function.....