How can I pass over a crane to my CAD-system if the relevant Button is deactivated?

Please check if you have a "graphics" license in use. Go to "?" » "Info". In the lower part of this information window you will see in the 4th line, if you have a "data" or "graphics" license in use.

If you have a "data" license, it is not possible to connect to CAD.

If you have a "graphics" license, please check if the Marker is set to "AutoCAD 2004 - 2010" or "BricsCAD V8 - V10" in the settings menu.
To check go to "Extras" » "General settings" » "CAD".

Please check, if your CAD system is an AutoCAD or BricsCAD full version that is supported by us.

Be sure that your CAD system is running and you are in the so called model space (not in layout or paper space) and the command line is not blocked by an active command. If the command line shows "command:............." your CAD system is ready. if not, the ESC key might help.