Why won't my 7 Segment light up? [w/ PICS]

I'm working with a 2.3" 7 segment and it will not light up. I can handle evey thing else once I get 1 segment to light up.

http://www.flickr.com/photos/51037744@N06/

You'll see wires go from pins 1 and 5 (red wires) to a bread board. The 3 green wires between them are pins 2-4 and also go to the breadboard.

From there, the green wires pass through a 180 ohm resistor and then exit to a digital pin in the arduino mega.

Power for the 7 segment comes from the arduino comes from the 5v out.

I have only wired the bottom of the 7 segment display because if it works, I'm going to flip the bread board to go behind the display and then loop the other wires around from the top.

Two questions... does the 7 Segment display take 5v from the arduino or does it need separate power?? Also, I've coded something on the arduino that turns pins on... But they don't turn on... so now what?

int ledPin31 =  31;    // LED connected to digital pin 31
void setup()   {                
  // initialize the digital pin as an output:
  pinMode(ledPin31, OUTPUT);  
}
void loop()                     
{
  digitalWrite(ledPin31, LOW);
}

Here is a link to the 7 segment data http://www.allspectrum.com/store/product_info.php?products_id=163

Also, I'm using an arduino mega, but the wireless shield on top of it has been taken off (even though it's on in the photos).

I'll answer my own question for the next guy. I'm using a SA23-11SRWA and the schematic says 1.85 V typical and 2.5V max. Apparently there are 4 LEDs per segment, so its 7.4V-10VMax.

I used a variable DC power supply and found that out.

What I would do...

For what I can tell from the Datasheet, the Arduino should be able to run at least one of the 7 segment displays, but to run all 4 I think is pushing it. I would use a 2803 transistor array to run each of the outputs or a 4-bit BCD to 7 segment that can do both the decoding and driver for the display.