Help with H-Bridge pls

Hi, I'm trying to set up a simple motor controller with an H-Bridge. It's all wired up and I have the Arduino programmed to run teh motor backwards and forwards with a 1 second delay between each change of direction.

The trouble is, the motor doesn't move. I have a multimeter connected to the motor outputs and it swings between +9V and -9V, without the motor. If I connect the motor, the voltage drops to +/- 0.4V.

I'm using a SN754410 H-Bridge with a 9V battery for motor power, and the Arduino for the logic power.

The motors are little DC motors that would normally hum along with a 9V battery.

Does anyone have an idea of what I might be doing wrong. :(

Thank you.

Did you connect the 9V battery ground to the Arduino ground?

Yes, both grounds are connected.

But...

I had a resistor between the ground and the Arduino. I took out and all is good now.

Thanks for the tip :)