Pumping Wet For Dumbshits Explanation Needed

I got some cylinders from Yinyangchi I’m going to review, however I need help actually pumping wet before I can do that. I’m relatively new to pumping with traditional gear (had bad experiences with Bathmate Goliath losing its seal) so this may be a really retarded question. Looking at the In Line Water Trap sold by Pumptoys it seems like a pretty idiot proof setup. I bought a Mityvac MV8500 kit which comes with its own water trap, put one end on the Mityvac, one end on the cylinder and it should all be good to go. But no. I get zero pressure from the pump when I try this. When I put the pump directly on the cylinder I get pressure, so the pump isn’t at fault (for that, problem with the pump described in another post). It also sucks water into the pump in about a trillionth of a second. Do I need to buy the In Line Water Trap from Pumptoys (or something similar, open to suggestions) to pump wet?