I don't have a solution for you, other than to remove the fittings and see if you can pump grease through them when they are out of the PT. If they work that way, you eliminate the first point of failure. Then you can look in the hole where the fitting came out of and see if there is anything in there. Make sure the holes actually go somewhere and are not plugged. Take a thin piece of wire and poke the grease in the hole. See if it is hard as a rock or not. Worse comes to worse, you may have to loosen up a joint and pump in enough good grease to get the old grease out of it, then tighten it back up and see if it then works.
Also, do a search of TBN for grease AND zerk. There was some discussion of this a few months, maybe a year, ago. Same thing... zerk would not take grease.
Hope this helps. /forums/images/graemlins/crazy.gif