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

arduino.cc/playground/Interfacing/MaxMSP

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