Touch screen not working after replacment

Hey.

Recently i have been given an iphone 4s by my brother to repair, it had a stuffed lcd and a shattered digitizer with no touch.

I replaced the lcd and digitizer as i normally do, lcd is working fine but there is no touch.

I thought straight away that i may have damaged the flux cable so i took it back apart and checked it, all looked good, so i tried the display assembly in another 4s, and both he display and the digitizer work fine.

I then tried another new lcd / digitizer in the phone and same thing happens LCD works but no touch.

Have given the touch connection a good clean and reinstalled the lcd many times to no resolve.

Have also restored the iphone.

Any idea's?