What is wrong with this controversial photo?

Do you see anything wrong with this photo? It has been causing a lot of controversy

If you can't pinpoint it, see the cause of controversy after the cut
The Yoruba traditional rulers in the photo have been criticised for kneeling when it was time to take a group photograph with the President who was in Ogun State on Tuesday on a state visit.

Considering the status of the president, is there a cause for criticism? Let's know your thoughts.