Sigma Flash Help (Slave Flash)

I can not get my new Sigma EF-500 DG Super EO TTLII flash to fire in slave mode with the infared set up. Optically is not a problem but I do not want everyone at a wedding setting off my off camera flash. I have 2 of the same exact flash and my goal is to have one flash on the camera (NOT FIREING) but setting off the off camera flash only. As of now, I can not get the camera to set off the other flash after reading the manual (which is straight forward…or so it seems).

This is the settings that should work but does not. You can see which flash is slave as it has the base on it. The other flash would be mounted on the camera. HELP!!! What do I have wrong?

http://fromtheflightdeck.com/temp/nycaviation/flash.jpg
Can anyone help

I think I have figured it out.... I was in Av mode and I must be in Tv or M and under 1/30th of a second to get the slave to fire..... Not sure about any other settings, but it is a good start. I was also able to turn off the main flash and use this as a trigger for the off camera flash. I have way too much to learn in very little time to get consistent results. My neighbors should be yelling "Lightning!!!" all night!

Ahhh, the fun of not understanding your new equipment (AFTER READING THE BOOK FROM END TO END!)
any tips would be greatly appreciated