Its possible that the port on your computer can't provide enough power to charge it. If it charges ok in a wall outlet that's more then likely your problem
I have had that problem on my PC at work. It is an older one and sometimes when I plug my Tbolt it, it gives me an error.
Also, I have a USB cable at work and another one at home. The one at home is loose when I plug it in directly to my phone. But when I plug it into the docking station....works perfectly and fits snuggly. Make sure the cable plugs in tight and doesnt' easily fall out