Hey there lisalau,
I apologize about the slow response time, thank you for being patient! Were you able to fix that heating issue? If not, I'd be happy to help you out. First, would you be able to go into your Nest Thermostats setting, and take a picture of your wiring, and upload it here, so we can look at it? That way, we can see if the wiring is being read properly by the Thermostat.
I look forward to your response, and if you have any other questions or concerns for me, please let me know!