Wanting to make a first effort at off camera flash, I bought a CTR301P, which won't trigger my EF 500 DG ST in any mode. Just noticed on the Gadget Infinity webpage the following warning "Some dedicated flashes (e.g. Nissin Di-622 and Di-466, Sunpak PZ42x and PZ30, Sigma EF-530/500 DG ST for Canon, etc.) are triggered via system-specific pins instead of the central contact of the hot shoe. Cactus V4 does not work with these flash models." It goes on to say that the Catus unit is okay with the EF 500 DG ST for Nikon only

So, does, the same apply for the CTR301P? There is no such warning on the PROtog website, but this seems to be the most likely explanation for my lack of success. Has anyone successfully used the combination that I'm trying?

thanks in advance