QL200 & Stepper Motor

I have a stepper motor " 42SHD0217-24B " and pic development board QL200. i wrote a simple program to run the motor. but it moves forward and backward (0.1 degree). Please give me a solution for that. Thanks.

void main()
{
TRISA = 0;

do
{
PORTA = 0b00000001;
Delay_ms(100);
PORTA = 0b00000010;
Delay_ms(100);
PORTA = 0b00000100;
Delay_ms(100);
PORTA = 0b00001000;
Delay_ms(100);
}while(1);
}