4Wire Bipolar Stepper + L293d

Hello, so I'm still pretty new around here, and also pretty new to electronics.

A week or two back I bought myself one of these; http://www.skpang.co.uk/catalog/product_info.php?products_id=673 datasheet; http://www.sparkfun.com/datasheets/Robotics/SM-42BYG011-25.pdf

and an L293d chip to operate it.

I wrote a very basic code, using the Stepper include, and plugged my motor direct to my Mega board. Worked fine, but with very little torque.

I then tried to copy this circuit; http://arduino.cc/en/Reference/StepperBipolarCircuit

For some reason, coil 1,2 works fine, but 3,4 does not. (I tested this by plugging wires 3,4 direct to the mega, and 1,2 through the L293d)

When I try to use the other half of the L293d, I get no results.

My circuitry is fine, with all the enables high etc, my input voltage is a steady 12 volts. Is half of my L293d broken? or am I being really dumb?

Thanks for any help

My circuitry is fine, with all the enables high etc, my input voltage is a steady 12 volts. Is half of my L293d broken? or am I being really dumb?

Have you had someone else confirm that the circuit is wired correctly? That would be my guess as to the cause of the problem.

Try switching the 3/4 wires with the 1/2 wires. Does this make a difference?

Post a photo of your wiring. Maybe that will help.

I'm unable to get a picture of my circuit, but I've had it checked and confirmed. It's identical to the one on the wiki reference page.

It's almost asif the left side (1,2) of the chip works fine, and the right side doesn't (3,4)

I've tried plugging both coils into the arduino = success One coil into arduino, one coil into 1,2 = success One coil into arduino, one coil into 3,4 = failure both coils into 1,2 and 3,4 = failure

could it be possible that one half of the L293d chip works but the other doesn't?

I've wired and rewired multiple times :(

Heavily wound up >:( ;D