Well, after a lot of test this is what i discovered.
Now i have two pc with calibre on
On the first one i have 0.9.3
On the second one i have 0.9.1
1)With 0.9.3 i put a book on the device, everythink is ok (library and
device info shows the green check)
I close calibre and reopen it
The book are not visible in the device tab nor in library tab (no green check)
unplugging the usb or restart the device does not change anything. i tried also a pc restart
After that I connect my device to 0.9.1 and.... I see my book on the
device (not in the library because the library is not update)
I close calibre, unplug the device
Now when i connect my device to 0.9.3 I can see the book on my device but not in the library (no green check on LIBRARY)
I saved all the files metadata.calibre and driveinfo.calibre and i see that after sending the book the metadata.calibre is full with a lot of strange character
I attach the file after insert a book. Do you think my library is corrupted ?
Tomorrow i will try to uninstall calibre and reinstall it.