I have had a solution in another discussion : the problem its about Mac , if you go in the preference Security/Privacy you can give again the acces to Lightroom at HardDisck. Anyway thanks for your helpSilvio
Click on COPY (yes, I know you want to ADD, but click on COPY anyway). Make sure the Destination Panel is present and points to a valid folder (a folder that actually exists). (If it is not present, right click on one of the Panel headers and select Destination). Then click on ADD.
Thanks , but now works again because the problem was about Mac : If you go in preference (mac) Privacy/Security it possible to give again the access to Lightroom at the Harddisk . The first time that you install software Adobe iMac asks the permission to give the access to Desktop , Download etc ; second time no , remain in memory the first chose .