120v to 50A cord

[TEO]

I had my 2018 Newmar 3124 over at my house today packing to leave tomorrow. I just wanted to power the fridge and maybe a couple lights. I got a splitter from my stepfather that has one 30A 120v male end and a standard 15A 120v male end, they come together to a female 50A 120/240v receptacle. I plugged in an extension cord to 15A male and nothing to the 30A then plugged my coach 50A cord into the end of the splitter. I thought I would have 120v in part of the coach but nothing. I looked for a wiring diagram for the ATS but couldn't find one showing the control side wiring just the line and load, Surge Guard #40100
I will add a 50A 120/240 eventually to my house but, in my mind this should have worked as long as there is power to one hot leg but the ATS would not pull in the contractor, I'm guessing the control voltage is being pulled off the leg I didn't have power on. Sorry for the rambling but wondering if I had a single 50A 120/240 to 15A 120V dog bone if this would work?

 

[Richpatty]

Maybe a picture of the adapters would help us?

 

[TEO]

This is not the one but just like this.
I see were if you had the 30 and the 15 plugged into a pedestal you would have 120 on each leg and the ATS would see it and pull in the contactor.
On the one I have I'm guessing the 30A is the leg the ATS uses for control power so it doesn't see the extention cord i have plugged in by itself. Just wondering if someone knows if the single dog bone 15A 120v to the 50A would put the power on the correct leg for the ATS to see and pull in the contactor?
Like this one.

 

[Richpatty]

I can’t speak to the one you have pictured as I have not used them before…. But a 15amp to 50amp would definitely work…