Okay - do you have the motor shield set for PLL or PWM? The function of the pins changes depending on how you have the board configured.
It would appear that the jumper by the double screw terminal block needs to be set properly.
In PWM mode pin 4 is motor 2 direction and Pin 5 is motor 2 PWM speed control, Pin 7 is Motor 1 Direction and pin 6 is Motor 2 PWM speed control.
Also - Yu don't give a complee listing - do you have you output pins defined properly?