Depp struggles with horse riding

London, July 2 (IANS) Actor Johnny Depp is struggling to master horse riding on the set of his latest film "The Lone Ranger" but insiders say he has not yet got to grips with his animal co-star.

"It has become a problem for Johnny. He wants to do all his own stunts, but he's been falling off his horse so often that producers worry he's going to do permanently damage his tailbone," contactmusic.com quoted a source as saying.

The 49-year-old is refusing to use a stuntman and is also growing increasingly frustrated as co-star Armie Hammer is a natural at horse riding.

"He sees Armie doing everything so easily, and that's got him even more frustrated," said the source.