Unresponsive touch screen with a case on

I have noticed that my iPhone's screen because somewhat unresponsive when I am not holding the phone, or if any kind of case is attached to the phone itself.

For example if my phone is connected to a docking station accessory and someone calls me then i can't slide to answer until i physically pick up the phone and do it. the same thing applies when i have a case on although it still responds to my touch but it selects things i do not tap on etc

this issue irritates me as i am unable to use cases on the phone (i have tested various of different cases which successfully work on other iPhones)

Please help!

I am using iPhone 5s with the latest firmware.

touch id does not sense my finger at all with a case on either