Trouble charging iPad via computer!

Welcome to the Apple Discussions.

Most laptops, at least those more than a year old, do not have enough power through the USB port to support the charging needs of the iPad.

The iPad will charge when connected to a computer or a laptop if the correct requirements are met. It will charge but very slowly. The recommended way to charge is to use the power adapter that came with the iPad that plugs into a wall socket.

This article talks about charging the battery in the iPad. See the section "Charging Tips"
http://support.apple.com/kb/HT4060

This article talks about USB support and requirements for the iPad.
http://support.apple.com/kb/TS1286

This doc refers to the Mac but it should give you an idea of the limitations of USB ports.
http://support.apple.com/kb/HT4049