is it charging?

Earlier today I tried to upload a movie to my ipod and the computer froze. I was in a rush so I didn't have time to mess with it. The screen on my ipod froze too. When I came home the ipod was dead. I tried to plug it up to my computer to charge and it will turn on for a second and say connect to power but why doesn't it recognize it as plugged up? why doesn't the charging screen come on?