Q: why my ipad is not charging when connected to my macbook pro?

Connect your iPad to a wall outlet with the supplied charger.  Not all laptops, including some MacBook Pros have enough power on the USB bus to charge an iPad.

It can be charged via the USB port if the port is high power...most laptops will have only one port that is high power so you need to either try each port to see if it will charge, or check the laptop specifications to see if they show a high power USB port.

The iPad needs a 10 watt port.

This knowledge base article explains the Apple computer USB port power - with a MacBook Pro the computer has to be powered up and not in sleep mode to charge an iPad.

You are welcome...and I realize how frustrating iPad charging can be...I just use the wall outlet all the time now so I don't have to figure out just wich port to use.

I've been a Mac customer for a long time and I just stumbled on to the fact that my iPad was not charging on my mid-2011 Macbook Pro.  Really.  It can only be charged on one port.  Thanks to the comments in this post I solved my problem, I plugged it into the other USB port.  Seems like a product deficiency, a corner cut.  Very unlike Apple.  And very confusing.