How come in software version 5.1 that when I add artists to my music; the artist will not show up on my ipod

Okay so i just recently updated my Ipod to the latest version for software wise (which is 5.1). So in doing so I lost all my music and had to put it all back in (Which was fine with me really). After I put this all in and re entered every single one of my artist back in. After i finished and synced up I look on myipod and noticed that some of my music is still missing artist info. I thought maybe it didn't sync or something so I checked back on itunes to see if I entered everything in correctly and I did. So I resynced and still added information on there. Before version 5.1 I was able to get artist information on there just fine, but after this update it would not let me get any of the music.

Extra Info: All the music I have gotten was not from itunes. I did not use apple products till about 4-5 years ago (First ipod touch and still using it). So i obtained my music all before itunes. I am not sure maybe that is why because I did not get it from itunes, but got it from another website maybe is why? Tho the flaw in that is because before this update I was able to add artist info and all, but up until the recent one I was not able too.