Pro Mini controlling a stepper motor

I purchased a Pro Mini 5v to replace my UNO that is being used for other purposes now. I am trying to have the Pro Mini control a stepper motor. Since I'm still new at this I followed a plan over at http://learn.adafruit.com/adafruit-arduino-lesson-16-stepper-motors/parts. I bought the parts listed from them.

The problem I am seeing is the stepper motor's shaft doesn't spin but the whole motor kind of vibrates a little. I tried this on two different motors.

I am keeping my Pro Mini connected to my USB cable for power

Hardware:
Pro Mini 5v
5V Stepper Motor
L293D IC

I wired up the breadboard a couple different times:

I followed the code example:
/*
Adafruit Arduino - Lesson 16. Stepper
*/

#include <Stepper.h>

int in1Pin = 12;
int in2Pin = 11;
int in3Pin = 10;
int in4Pin = 9;

Stepper motor(768, in1Pin, in2Pin, in3Pin, in4Pin);

void setup()
{
pinMode(in1Pin, OUTPUT);
pinMode(in2Pin, OUTPUT);
pinMode(in3Pin, OUTPUT);
pinMode(in4Pin, OUTPUT);

// this line is for Leonardo's, it delays the serial interface
// until the terminal window is opened
while (!Serial);

Serial.begin(9600);
motor.setSpeed(20);
}

void loop()
{
if (Serial.available())
{
int steps = Serial.parseInt();
motor.step(steps);
}
}

I also tried modified the code so it loops spinning back and forth with a one second delay. The vibrations occur every second on queue. Is there some issue with the Pro Mini 5v that would cause this setup not to work ? Any ideas or suggestions on what to try ?

Thanks

The code you've posted Looks odd to me.
Where does it set the direction?
Does it wait for you to send the number of steps via the pc-keyboard?
E.g. 5 = 5 steps ClockWise or -7 = 7 steps counterclockwise...

It seems to wait for some Input through the Serial port...

Correct, the sample from AdaFruit did wait on input from the serial monitor. positive numbesr spun forward, negative reverse. I also did a quick mod to the code to loop spinning and changing directions every second. Same results both ways, the motor just shakes a tiny bit.

Vibration in a stepper motor often means you've miswired it - identify the windings and make sure each
goes to one channel of the driver. A+ and A- to one H-bridge, B+ and B- to the other