About 9 months ago I installed a Progressive 50 AMP management system. On several occasions we have hooked up to a power pedestal and i get an "E1" code (reverse polarity) and no power to the trailer. Note, if I bypass the EMS I get no power to the trailer either. Usually I can move to another site and all is good. I have noticed other trailers can move into the affected site and they have no issues with the electric supply. Today we pulled into a Good Sam site and i get the same code with either 30or 50 service. The technician looked at the pedestal and told me they do not ground each individual pedestal and that is why I'm getting the code. Could I have a problem with the Progressive device. Any suggestions will be most appreciated.