The wireless master capability of the 7D is designed for Canon's optical wireless remote slave flash control system. It sends out two or five byte command sequences prior to flash triggering, in order to command and control the slaves. Several of Canon's own flashes are compatible with this system, as are also several third party units. Flash units requiring separate triggers usually work only as "dumb slaves", i.e. reacting to the single flash from a manually controller flash gun, or possibly to the second flash from an E-TTL system, which emits a measuring flash prior to the illuminating flash.
I use only Canon's flashes to avoid this issue, but that's a general answer. Someone who knows about the specifics of your models can probably give a more specific answer as well.