Help needed, Pioneer DMH-A240bt

[Emil0048]

I need some help with my "DMH-A240bt"

I'm having problem wiring up my subs... The unit onlt have 1 single female RCA output for subwoofer.

And i can't seem to get any audio signal from it.
I've tried several diffrent rca splitter and none worked so i went all out and bought an expensive one form amazon.
but it still wont work. The amp has power and has worked previously with a different headunit so that should not be the issue.

Any help appriciated. Cheers