Itunes Sync problems with my iPhone

Itunes recongises my iPhone but has syncing problems.
Once connected, and pressed sync it does the normal backing up, preparing for sync then it just finishes. I am not sure why, my new music are not on my iPhone this is really frustrating. Can anyone help me with some suggestions?
I have tried reinstalling itunes and i am on the latest itunes 10.
iPhone 4 running on ios 5 and it is jailbroken
Windows 7
Thank you
Answer #1
In iTunes click your iPhone name on the left side then click the music section and check the option ‘Sync Music’
It should work, though im doing this from memory as im not on my computer at the moment
Answer #2
Thanks for the reply,
It is not working.
It was working last time i sync my iPhone (1-2 months ago) hence there are still some music on my device but i cannot add or remove due to this
syncing problem.
More suggestions please?
Answer #3
Once connected, and pressed sync it does the normal backing up, preparing for sync then it just finishes. I am not sure why, my new music are not on my iPhone this is really frustrating. Can anyone help me with some suggestions?
You must have the music list on your Itunes when you sync. Otherwise all the tracks in your iPhone which is not present on iTunes will be deleted.
Answer #4
Music list is on my iTunes. That was not the problem, after days of digging i finally found a rare but easy solution to this problem. Thank you for your reply guys, appreciated.
Simple Solution –
While iPhone is connected to iTunes, Sign In to iTunes, Window will pop up and just click “Authorize iPhone” and your good to go.
Not sure why it unauthorized my iPhone but that’s the way it is
Cheers