Oil Pressure

I just installed the 360 went to prime the engine with oil Royal Purple break in oil. It seems like it is taking forever to get the oil to everything. There is no pressure at the gauge. I pulled the line off and oil came out the fitting when the pump was turned but nothing goes into the line when it is reconnected. The passenger side lifters pumped up but the drivers side are hardly are getting any oil. I rotated the crank by hand stopping every 90 degrees two complete revolutions and more while turning the pump with a drill. It is a brand new Melling pump m72hv. Any ideas what the problem might be?