Max Msp, Arduino and LED's

Hi there, I have a question about the reliability of lighting LED's through MaxMsp.

I'm using the Maxduino maxMsp files found at

and the Standard Firmata on the Arduino.

My problem occurs when lighting LED's, all other functions work great! I can get an LED to turn on and off by clicking on the digital output section of the patch. But for some reason it doesn't see to work 100% of the time.

Any thoughts?

Many thanks