There are a few possibilities:
- A robot can only be connected to one Choregraphe session at a time.
Make sure no one is already connected to your robot with Choregraphe. - Make sure your Choregraphe version is the same as the NAOqi version.
- Make sure NAO and your computer are connected to the same Network.
- If NAO has not been correctly disconnected from the last Choregraphe session, you will get an error message.
Just reboot NAO to solve this issue.