This means Alexa might not be able to understand the name of your ecobee. Here are a few things you can do:
Make sure you’re using your ecobee’s name correctly. To confirm what you’ve named your ecobee, on your thermostat, go to Settings > Preferences > Thermostat.
Make sure that your ecobee’s name is easy to understand. For instance, Alexa will have trouble understanding ‘ecobee3 lite’ or a name that is spelled differently (such as 'b3dr00m').
You can change the name of your ecobee at any time by going to Settings > Preferences > Thermostat > Input the new name. Once you’ve changed it, you’ll need to ask Alexa to discover devices again.