do i have an airlock?

heated water doesn't seem to be circulating

I just finished building my radiant floor/baseboard system using a Burnham Rev 4 boiler and a honeywell AQ675 controller with a 6800 series 3 way mix valve for the rad floor section.(baseboard part is 1 1/4" Cu stubs valved off for now). This all went in an existing house so I hung the 1" Cu for radiant and 1 1/4" Cu for bb on strut under the house. I put an air scoop/expansion tank with a float vent downstream from the boiler on supply side before it drops down under the house and i put a float type air vent on the return side at the high point where it comes out from underneath back into the boiler room. I fired it up and everything was going great except the hot water didn't seem to be circulating to my downstream manifold. I could feel hot water at the mix valve and past the pump but not much further. About 15 feet downstream from the pump I plumbed in an el pointed down then a T going one direction then below that another el headed toward the manifold in question. I did this because i had to change elevations of the pipe as well as send the water in different directions. My question (finally) is did i create an airlock at the point the pipe drops down? If so do I need air vents on both supply and return? Thanks for trying to make sense out of this long post.