Why does my brand new htc m9 stop charging when the screen is off?

[Charging Question]

I bought this phone four days ago. Tonight when I put it on the charger (at 50%) the led indicator flashed for about twenty minutes. I figured there was a shortage in my cord so I moved it around some but it didn't work. I left it alone due to frustration and I noticed it stopped flashing. But, when I turned off my screen the led indicator, again went off and came back on. The screen popped back on and the light was steady...until the screen went black again. It won't charge unless the screen is lit. Why can I not turn my screen off to charge my phone??!