iPhone 4 was working fine with dock now not connecting

Hi

I have a iPhone 4 and used to connect to a disgo tv iPod docking system and it played by clips and music. After a system up date on my phone last year it would connect to my dock. The rest of the features on dock work fine and after some research I see there has been quite a few with same problem. I can't see if anyone got a solution to this and thought I'd have a go on here.

If any one can help it would be greatly appreciated.