Can't Put Music Onto My iPod Nano:(

I have an iPod nano 5th generation, software version 1.0.2 but when I plug it into my laptop now it won't put music on it. An error box appears saying, for example: "Set Fire To The Rain" was not copied onto the iPod "Andrea's IPOD" because it cannot be played on this iPod" but I don't know why it's doing this. I authorized the computer and it won't download songs that I've purchased through iTunes, from CD's, nor the ones that i converted from YouTube. Please help, any kind of help would be greatly appreciated 🙂