New Heat pump, heat strips not working.

Just built a new house, installed a Rheem Heat pump, now that its in the 30's, it was not warming enough, installer came back and installed 5 KW heat strip. Problem is, the Honeywell visionpro TH8000 does not kick the heat strip on, it cant get over 72 in the house, so it turns off, and in 5 minutes tries again, over and over.. If I raise the heat to 76, "Aux Heat" text comes on, BUT, turns off in about 2 minutes and never gets warm. If I switch to Emergency Heat, everything turns off. My installer seems lost, I told him about installer setup codes, even more lost. Any advice I can give him?