PWM motor code - difference between Romeo V1.1 and V1?

Hi,

while my broken Romeo all in One V1.1 board is in the replacement process I bought a Romeo V1.
This PWM code worked fine on the V1.1:

void advance(char a,char b) //Move forward
{
analogWrite (E1,a); //PWM Speed Control
digitalWrite(M1,HIGH);
analogWrite (E2,b);
digitalWrite(M2,HIGH);

Now on the V1 I need the code below to have the robot move forward:

void advance(char a,char b) //Move forward
{
analogWrite (E1,a); //PWM Speed Control
digitalWrite(M1,LOW);
analogWrite (E2,b);
digitalWrite(M2,HIGH);


Polarity on the motor hasnt't changed. Red cables go to +, black cables go to -.

Any idea??

Thanks
Robert