[Greg McKaskle]

There are many ways of doing this. My guess is that putting the code into Robot Main had it run in parallel with Begin, and therefore not get valid references. If you want to use this pattern for something else, go ahead and place the code into the subVI Periodic Tasks. Unless you are going to guarantee that Begin completes before your code requests the I/O references, it is best not to put code into Main.

Greg McKaskle