Canon Eos Rebel: Flash will not pop up in full-auto mode...

[LanceTrottier]

EOS Rebel XTi DSLR. Even with nothing else attached... Occasionally use a Bower Auto Focus add-on flash, model SFD35C.

[Skirball]

If you push the flash button does it pop up?  Either something is physically restricting the flash from popping up, or the camera thinks that something is preventing it (there is a little button underneath one of the rails on the hotshoe that senses if anything is in the shoe.  Sometimes putting a flash on and off a couple of times will release it).

[Kwiat95]

I have used the SUNPAK flash in my EOS Rebel T2i . I just used it one day taking photos at a birthday party .

Few days later  flash stoped working even with new batteries. I removed the flash to be surprized that now my camera flash stopped popping up. I found that pinsize buttton on a right side guide of the hotshoe and used a small screwdriver to lift the metal contact above the button and I had to push the button few times but it worked.  Thank you very much.