Why can't my iTunes convert my music?

Okay so I used to use my iPhone 3s to convert music from my Mac OS X to the iPhone 3. Now I got the iPhone 4S and all my music from the old iPhone is still on the iTunes account, but it won't convert to my iPhone 4S account. Can someone tell me how I can get my music to my iPhone 4S?

Did you use the same apple ID for your itunes account on the iPhone 4s? If it's bought music all from itunes it's account bound and can only be used with music connected to that account.

The word isn't "convert" - that's making a copy of a media file in another format, like wav to mp3.

"all my music from the old iPhone is still on the iTunes account, but it won't convert to my iPhone 4S account."

Iphone account? Do you have more than one iTunes library on your computer? I don't know why you'd have separate iTunes for a device if you own both devices.

Do you just mean that you haven;t been able to get any music onto your iPhone 4s from the computer? Your question doesn't say how you tried to do this or what happened when you tried - those are the most important details.