I got a zoomed 501 external filter canister to work for my 55 gallon tank. I have it setup pretty much the same way you have on your sketches.
See:
I hope you can see the intake and the outflow.
ANyway, I had some trouble getting my canister filter working too. I had to fiddle with it just to get it to prime, but It worked. Now I havent serviced the filter since that pick was taken in November or December, and I have to clean it now. Oh boy. Keep working on yours, I bet that it will end up working for you eventually.