Help! My new ipad will sync everything, but my music!

I just got a new ipad and I connected it to my PC and opened iTunes, it synced all my apps, my pictures, but it won't sync my music. I have tried clicking and unclicking. Adding one album or song at a time, but it won't work. My computer shows the music in gray with a dotted circle by it, but it won't begin to upload it to my ipad, and when I click on my music on my ipad, it shows an empty folder. Please help me, I'm so frustrated.