IPhone 4S won't charge unless off?

My iPhone 4S will only charge with it off and when that happens its very slow. I tried computer charger wall charger I've tried everything and the phone only charges when it's off. Anybody know how to fix this?

Just let it charge

It is charging slow because energy is still being consumed. When it is off no energy is active or being consumed. Or it is charging slow because you still have some apps running. You might think they're off but they are not. If you already have a task killer pre installed in your phone close all of your apps. If you don't have one then download one from your app store. Then try charging it. If this doesn't help go to your network store (such as tmobile sprint metropcs etc)