er99 with my 10d, 17-50 Tammy, 550EX

Sorry for the long first time post everyone

What do you guys think? I've had the Tammy 17-50 for nearly a year, along with my 10d, 70-200 4L, and a new EX 550 that I just bought. I've used both lenses tons, zero problems. Bought the 550EX used, used past 3 days with both lenses no problem. Started shooting some newborn puppies tonight with the 17-50. Played around holding the camera directly over them, and shot 2 times without directly viewing. On the third shot like this I got the ERR 99.

Replaced batteries; switched to 70-200....works fine. Take flash off, try Tammy again.......no go. Tried everything I can think of and I get a err99 with the Tammy and my d10. Gotta wonder if my holding it the way I was and pointing down had a play in this...............
Help!

Hmmm could be. Try cleaning the metal pins on the lens, and maybe see if pushing it up into the body whilst taking a photo like you described helps. If that works, then I guess it's loose somehow.