Works, but not all flashes

The purpose of the exercise: I have two old flashes a Metz 30BCT4, with triggers for high voltage for modern cameras and a Canon Speedlite 299T from my T90.
I shoot with a Canon D90 D40x and and can be used as a manual flash on the camera only the Speedlite, because I thought to myself, I can use the flashes as a side effect brighteners or lights. Works unfortunately only at Metz, the Canon resolves, as here already described often only once, then it must be switched off briefly, then it goes again. Schade has yet everything I need, but also enough of Metz.
So, the older of the flash, the more it works. Attention, the pre-flash my Samsung NV8 fires the flash and the Nikon measurement flashes in iTTL trigger, so just for the manual photography, but the promises of the flash trigger only! But but, of course, so far the lightning participates to 1 / 250stel. Also extends the strength of the flash in a room to a side, top positioned flash trigger with my D90 1 / 50th.
So great for the price! ATTENTION with all modern flashes of Canon there like other triggers also problems, this has to do with the Canon private behavior of lightning, so the older the lightning more likely it is connected well here. Tripod mount is made of metal.