Servo control guidance

I am trying to run a JX PDI-HV2060MG High Torque Servo.
Here are the Specs

Brand: JX Servo
Item: PDI-HV2060MG
Dead band: 4μs    1520μs / 330hz  
Max PW:650-2350us ,180° compatible (don't exceed max PW)
Standard PW: 850-2150us
Motor: High quality core motor
Operating Voltage: DC 6.0V-7.4V
Operating Temperature Range: -20 — + 60°C
Operating Speed: (6.0V) 0.15 sec/60°
Operating Speed: (7.4V) 0.13 sec/60°
Stall Torque: (6.0V)  48kg.cm
Stall Torque: (7.4V)  62kg.cm
Dimensions: 65.8X30X57.4mm
Weight: 200g
Bearing: 2BB
Connector Wire Length: JR 265mm

I can not get it to work at all, running an arduno Uno out of Pin 6 (digital) with 7.4v externally powered.

I can run a small 9g servo, but for some reason this wont work.

What am i doing wrong?

Thanks for the Help!!

StrikeforcePC:
What am i doing wrong?

You are not showing us your code. Remember to use code tags.
You are not showing us your wiring diagram. A pic of a hand drawn diagram is good enough.

Did you connect the Arduino and 7.4 V power supply grounds?

jremington:
Did you connect the Arduino and 7.4 V power supply grounds?

That solved the problem!!!!!