Programmatically Toggling a Boolean Control

[Anatole]

Thanks for the replies!
I've got to the next step.
I have another problem -- now, when I'm running a while loop in one of the case sequences, there's no way I can stop this loop outside of the loop itself. Here's the vi I'm using:
I try to use the cancel boolean, but it doesn't change any values, because the while loop is running.