Iphone sync failure

although my itune account info states that both my mac and iphone are authorise for purchases when i try to sync my iphone when connected to mac a window pops up and states that this computer is not authorised? I have checked that it is authorised and have then deauthorised it and authorised it again but same message pops up telling me it is not authorised I seem to be in a loop here`

Go to the iTunes store in iTunes, use the quick links to go to account information and check under iTunes in the Cloud > Manage Devices to see if your iPhone is associated with the iTunes account you are using.

Hi if I can refer you to my post at the beginning it states that I have already done what you suggested to no avail that is why I am seeking an answer but thanksanyway

There is a difference between Authorised and Account Association. A device can be Authorised to download iTunes content but that does not mean it is associated with the Apple ID you are using to log into iTunes. In fact if it has been newly associated with that account you need to wait 90 days before you can download content.
Can you provide a little more information about;
What OSX you are running on your computer and
What iOS on your iPhone?
There have been a lot of changes lately especially to the music apps on both phone and computer.

Hi Rod I was taking your advice and checking what ios was on my phone and I noticed it was identified as Iphone (3) and realised that on itunes it was identified as iphone (2) so I renamed phone as iphone (2) and hey presto now syncing as required thanks for your advice
Cheers
Ben