Oil Pressure in SBC

[6camaro9]

I fired up my brand new ZZ383 today and the oil pressure gauge would never pick up and show any kind of pressure. I took the valve cover off the passenger side and I have plenty of oil sitting in the head and around the rockers. The sending unit is mounted about the oil filter because I can not get the plug out of the top port beside the distributor. I was wondering if I might just have a sending unit bad on the autometer gauge or if I am actually having oiling problems. What do you guys think. Thanks for the help.