robtillaart:
please post the whole code, only an error message is so difficult for us...
Thanks for the reply. It turned out that my ArduinoIO folder within my MATLAB folder was not on my MatLab path. I've now put the ArduinoIO folder on my path and moved my "buttons.fig" and "buttons.m" files within the folder and its working fine. And its working fine in the command window.