Just seen this topic which I hadn't picked up on before.
Your problems are due to the SDK4 Jukebox not keeping to the established YAMJ file naming standards, and the odd 'rogue' character in a file name will cause the display to be blank. This issue has been discussed in the YAMJ forum on a good few occasions.
The restriction on movie / TV series file naming is documented in the YAMJ wiki
Check you file naming, then rebuild your Jukebox and it should work out.