Having same problem

Question

The Totaline thermostat up button won't work when it gets colder at night and I try turning up the heat to get my house a little warmer. Its like its locked but the down button works to lower the heat temperature setting. I don't understand what could be the problem I done tried everything to figure it out but haven't found a solution to the problem yet. I was wondering if anyone else out there could help me with this?