New Flash, newbie needs help

I'm hoping that my ignorance is the problem and not the flash, but i just today got the Sigma 500 Super and I have no idea how to use it...of course I bought it used and it doesn't have the manual. i just want to leave it in ETTL mode for now and I can't get the flash to fire. (without hitting the test button that is)
any help would be GREATLY appreciated!
thank you so much, i'm just so excited about my birthday present, and i can't get it to work! URG!

you dont say anything about what camera you use it on?

oops, so sorry...thanks, its the rebel xt.

As long as you have the flash in ETTL mode, you should be able to just mount the flash on your camera and take it from there. Maybe there's something set that's keeping the flash from firing although I can't think of what that could be. Can you describe what's on the flash LCD screen? Do you see any lighting symbols under the word ETTL on the left side of the LCD?

I see ETTL in the upper left, ZOOM 17mm off to the right,
and a blinking picture of what looks like the flash at the bottom left corner of the screen....I bet thats it isn't it? what does that mean?

oh, nevermind, that blinking was because i didn't have the rotation part locked into a position, but i do now and its still not firing!
when i hit the shutter 1/2 way i see the red light shining and blinking onto my subject, but the flash never goes.

How about in the viewfinder of the camera, when you have the flash mounted and turned on, does a lighting bolt appear at the bottom of the viewfinder to indicate that the flash is on and ready? If not, then you might have a defective flash.

Try setting the camera and flash to manual mode and see if it works that way. To set the flash to manual mode, press the MODE button until a "M" shows up on the flash LCD screen. Set the camera to 1/60 and see if the flash fires in this mode.

no lightening bolt in the viewfinder.
and no flash in manual mode either.
GREAT, this was bought used on ebay...nice birthday presnet, I'm so bummed.
is there anything else you can thing of that I might have done wrong?
thank you for your help by the way!

I'm afraid I've run out of ideas. Sorry. You could try calling or emailing Sigma.

One other thought just occurred to me. Are you sure that flash was made for the Canon and not some other brand? Although if the LCD did say "ETTL" then it probably is a Canon dedicated flash.

i'm going to call sigma in the morning...and yes, its dedicated for canon, the guy that had if before me used it with his 300D.
Bummer....please if anyone else has any ideas, start shoting!

There should be a distance scale at the bottom of the LCD screen when you half-press the shutter button. If it's not there, then it's not communicating with the camera for some reason.

Did you check your CF, #5.3 maybe which desables the flash ?