It sounds like your creating the CANTalon variable, but not calling the new operator.
Take a look at section 3.2.3 in the Talon SRX Software Reference Manual. See the line that reads...
Code:
CANTalon customMotorDescript = new CANTalon(0);
It sounds like you are just doing
Code:
CANTalon customMotorDescript;
The number you pass into new CANTalon(x), is the device ID of the Talon. Use the web-based config to set the IDs of the Talons so that each one is unique (See section 2 in the Talon software reference manual).