Futaba transmitters typically require that you reverse the throttle channel. On Futaba the ESC/throttle plugs into channel 3.

Remove the prop.

The ESC won't arm, typically, unless the throttle is set to zero. If you have not reversed your throttle channel, then set the throttle to full. Now power up and see if the ESC will arm. If it does, then operate the throttle and see if the motor runs.

Once you have confirmed this, go to your throttle reverse and reverse channel 3. Problem should be solved and throttle should work normally.

This may also be helpful:

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC FLIGHT
http://www.rcuniverse.com/forum/m_7100376/tm.htm