Itunes won't sync music to my iphone 5?

I have a mac and i have an iphone 5. Both are fully updated and i have to latest version of itunes. When i click the box that says sync all music i click it and then click sync it acts like its going to sync and then it skips the part where it adds all the music and the bar at the bottom that shows storage goes down! I can't get any music on here but everything else works please help i don't know what to do!

The likely reason you are having problems syncing is because… You insist on syncing your iPhone instead of using manual management. I've used manual management on iPod Nano 1 & 3, iPod Touch 2, 3, and 4, iPhones 4s and 5 and iPad 3, so anybody who says you can't is an idiot.

MM is superior to syncing. I've used it to put hundreds of songs on my own iPod. Nothing gets on or gets erased unless I want it gone. I can always put the songs I want on.

If you are still having problems - did you recently update your iTunes software? If so, did you remember to restart the computer?