no oil pressure in 95 nissan pickup?? Help!

:banghead: Recently the timing chain was replaced in my 95 nissan. all was well till it was started and there was no oil pressure. then the oil pump was replaced allthough evrything ive read says they never go bad. it didn't work. evrything is cleaned out there is no blockage and this was not a problem before the timing chain. Any ideas would help because i am running out of them. Thanx.:frown:

did you prime the oil pump ??