Newb question - my plugin quits working after a while

[NermNermNerm]

I'm sure that there's a FM somewhere that I haven't R'ed, but...  I have a simple dialog and a toolbar button that I'm trying to get right.  The dialog pops up and works correctly when I initially load the game.  I get my little dialog showing up, and I get the toolbar button.  If I enter the VAB, the dialog goes away - but the toolbar button remains.  If I back out back to KSC, the toolbar button disappears and the dialog is gone too.  There doesn't appear to be anything in the output log to suggest any reason why.  My log messages just quit turning up.  Could somebody gimme a clue?

https://github.com/SteveBenz/ColonizationByNerm/blob/master/src/DebugControls.cs

 

[NermNermNerm]

Solved - I struck a land-mine.  I had copied an example from something that had KSPAddOn.KSPAddOn.once = true.