External power

I am new to this stuff. I have looked over the Arduino page and now I am stumped. I have run a bunch of simple sketches through the USB. I uploaded the blink sketch and removed it from the USB. I plugged in my battery pack, 5xAA tip positive jack, and all I get is nothing. I read that there is a jumper involved in older models however I don't see one on this board. Am I blind or is there something I just don't get?

Do you have a multimeter? Are the batteries good? Is the tip actually positive? When that batteries are plugged in, do you measure 5V on the Vcc pin? What do you measure on the Vin pin?

5 is a strange number of AA batteries. They usually are used in sets of 2, 3, 4, or 6.

After posting I took some time to look at the battery pack. It was so tight it was holding one battery off of the terminal. Shoulda thought of that before posting!!!