Cover Flow Problem

Hi , i have a problem in my ipod nano latest generation ( 16 GB ) . When i put new songs on my ipod the albums coverflows doesn't appear on the ipod but when i play them on itunes the cover flows shows . In the other hand, old music that i have in the ipod is showing the cover flows but not the new one ( from 5 days ago ) . I have another ipod and same model and i put the same music files in the other one , it works properly but i don't know ... y it not show in the other one ?? any suggestions ?!?!

 

no one knows about it ???