Can't get music from ITUNES to IPHONE

I am currently running the latest version of Itunes and the latest OS on my IPhone 4S.

When i try and send my music files from my mac to the IPhone via ITunes, it does not sync them. My Music folder is empty. Even when i try and do it manually from ITunes it still does not work. When i go on the sidebar of iTunes and select my phone icon (when it is connected) then select my music, there is a list of my music there but I cant find any music on my IPhone. I know it stores them automatically within the music folder on the IPhone, but mine is empty. Everthing else syncs wonderfully (photos, contacts, etc.). Very frustrating. Have tried to auto select and manually select in the ITunes app but nothing in my Music folder on my phone. HELP