Help with dumpvalve and double wastegate on turbo?

-I have bought a new turbo for my car with double wastegate. I have got the car to work as i should, but no dumpvalve will work, no matter what. I have tried 4 different dump valves, even on 1.5 bar it wont go off.



I have a Volvo 940 Turbo 1995 mod, and when i had the stock turbo i only needed like 0.3 - 0.4 bar to make the dumpvalve go off.



So now i can't figure out how to fix this, do the double wastegate on my turbo make the problem ?

On my turbo now it's only one wastegate that is used, and one is open. Should i connect them both together?



Thanks for the help :)