I'm curious, are you trying to connect the ET with the 920 selected as the platform or the Typhoon H? As I have not tried an ET camera I do not know for certain but it's possible the 920 platform may not recognize the camera software, and may require connecting as a Typhoon H to shift the OS into a mode compatible with accepting the software.
Looking at the U.S. Yuneec website I did not see any reference to the old CGO-ET, only one for the model compatible with the H-520. There's nothing I saw in Support or Downloads for the old model now. You might try calling Yuneec C.S. and see what they have to say. As the 920 can be operated as a Typhoon H by selecting CGO-3 from the camera drop down list the old ET should function.