Wireless flash with nex 7

I just got an F20AMon Saturday.  It seems to work fine in normal flash mode, but when I tried to get it to sync with my Nikon SB-600 flash unit, the SB-600 doesn't respond.  NEX set on wireless.  SB-600 set on channel 1 (group A if that matters).  The F20M makes two weak flashes when the camera is triggered (in wireless mode) but the SB-600 won't flash.  Any suggestions?