First: Is your trainer/sensor supported?

Dongle compatibility

RGT supports only USB2 compatible ANT+ dongles. USB1 dongles will not work within RGT.

No ANT+ USB dongle is not detected

Please make sure your USB ANT dongle is plugged in the USB port. If it is, unplug the dongle and plug it back in and click on the Trainer tab to force a search again.

ANT+ USB dongle not available - The device is being used by another application

The USB ANT+ dongle can be used by only one application at any given time.

The most common cause for 'No ANT + USB dongle detected' is another application using the dongle in the background. Please make sure there are no applications (such as Garmin Connect, Zwift, etc.) running in the background. 

Also make sure that your trainer is not connected to your phone or tablet via Bluetooth

Here is how to check what background processes you have running and how to end them:

Here's a how to on MacOS:

Here's a how to on Windows:

Some trainers use a proprietary ANT+ protocol instead of the open standard and cannot be used with RGT. Please check your trainer's specifications and ensure it is FE-C compatible. What trainers are supported?