Why charging phone case won't charge?

[Philip01]

The case it's self won't charge I was using it one night and it have one bar or charge left and it was blinking so I separated it from my phone and pluged it in so it would charge but when I pluged it in none of the lights would come on like its suppose to however when I put the case on my phone and charge the case at the same time my phone charges?? What's wrong with the case



cell phone cables