Canon rebel xt flash problem

[YokotaS13]

So i picked up this vivtar auto focus zoom 728afc flash from the airmans attic today. And its for Canon, but i cant get it to work with my digital rebel. However the lens i just took out of the case from my VIntage 1984 Canon 35mm works perfect with my Digi rebel


any ideas?
these are the two flashes, i think you can tell whats from 84
http://static.flickr.com/88/248151463_78844e606b.jpg
http://static.flickr.com/84/248151406_4a54369916.jpg

Any idea?
the lens is getting signal from teh camera the auto check lights up when the camera is working in liek autofocus and stuff, but i just cant get it to work.

I just realized how good a flash is...i took a ahot at daytime speed with the dinosaur flash and it turned out as well as an exposure 5x longer

[Nemesis]

can you attach the images? I cant view them at work.