Servo stalls(?) on Arduino IDE sketch "Sweep", what could be wrong?

I'm trying to test my new Futaba S3003 servo using the example sketch "Sweep" and it just wiggles and then stalls and wiggles a little, it never sweeps. What could possibly be wrong? I do have the wires connected correctly. Power supply is 5v and up to 700 mA (via DC wall adapter connected to breadboard via terminals).

Typical way to wire a servo for external power.

Crap, didn't realize the arduino ground needed to be involved. It works now, thanks. I didn't damage anything By not connecting the ground did I?

You couldn't damage anything, there wasn't a circuit so no current could flow.

Two bits of equipment connected by a single wire are simply acting as antennas
for each other, its not a circuit until two wires are involved so (non-RF) currents
can flow.

700mA is a bit close for comfort - servos often take more peak current.

Really? I tried researching the current draw of the S3003 and most places said 150-500 mA. What kind of battery power would you recommend if I wanted to use this servo on a obstacle avoidance robot (to sweep the sensor)? I'm going to start with my little TowerPro SG90 9g servo, but I got the Futaba as well in case the little one doesn't last long.

You couldn't damage anything, there wasn't a circuit so no current could flow.

Well if the servo "wiggles and then stalls and wiggles a little" current is flowing. Current may flow from the servo +v input somehow out the servo control line when the line is low. I know the 9g servos act erratically and get hot when the servo ground is lost.