Q: My iPhone 6 won't sync with iTunes version 11.4

Hello Adzi1978,

I understand that you unable to sync your iPhone with your computer. Let's see if we can get that sorted out .

Now I am not sure what kind of computer you have, but take a look at the system requirement for your iPhone. You will need to either have at least OS X 10.8.5 or Windows 7. Take a look at the link below for more details. 

Syncing with iTunes on a Mac or PC requires:

• Mac: OS X v10.8.5 or later
• PC: Windows 7 or later
• iTunes 12.3 or later (free download from www.itunes.com/download)

iPhone 6s - Technical Specifications
https://support.apple.com/kb/SP726 

Let me know what operating system and I can tell you what your options are as far as upgrade. If you are running a Mac, the next link will give some information on how to upgrade your version of OS X. 

OS X El Capitan
https://support.apple.com/en-us/HT201475

Take it easy