btw, this does not work as you supposed it to:
Case $NavExecutable < "10.1.0.394" or ""

there is comparison before the or and after the or.
kixtart treats empty string same as 0 or false.
thus, your or part does nothing but adds extra strokes to your script.
what you probably try to do is:
Case $NavExecutable < "10.1.0.394" or $NavExecutable = ""
_________________________
!

download KiXnet