I had a meal not post so I called. They had me send my CC statement. They found yet another meal at the same restaurant from earlier that did not post. I explained it was because I had gotten a new card and forgot to register it until later (I registered between the first and second missed dines). She said "no problem" and submitted the whole thing for processing - I got points for it all.
She told me the time frame you have and I think it was a month. Definitely call them!