Unable to charge my iphone 4s with charging chord when my phone is on while charging is possible when my phone is switch off? what i should do to get back to charging when phone is on

I have one iphone 4s and when i am connecting it with power chord then unable to charge it while when i am power off my phone and connect my power chord it start charging but again once apple logo appear on screen and phone start functioning then unable to charge my phone

So is there any hardware problem or do we need to perform so caliberation..

please help me with your valuable insight.