With Nodekit 0.7.4 and below, sometimes the Tagtool controller (the Arduino with the sliders and the button) is not recognised by the Nodekit although it has been working correctly before. This should be fixed in versions 0.7.5 and above - if you still experience this problem, let us know on the Tagtool Discussion group.
Here's a work-around for Nodekit version 0.7.4 and below:
1. Start the Arduino environment and load up the Tagtool Arduino program (as found on the DIY page)
1. Re-upload the program to the Arduino (making sure the right Arduino board version and serial port are selected under →Tools).
2. Close Arduino environment and start the Nodekit Tagtool patch - the Tagtool should be recognised now.