If the signalisation light on the Mini Dimmer is green, it means that the device is included in the gateway. In case the Mini Dimmer is not included in the gateway, but the green led is constantly on (no blinking) it mean that has the Node ID assigned, you will have to exclude (even if is not resulting included in the gateway) or reset the device.

After the exclusion or the reset is done correctly the green led will be blinking again, at this point the device can be included in the gateway normally.