I think the easiest thing for us gurus (...place ROFLMAO smiley here...) would be for you to place what code you've got so far here so we can see if it's a simple syntax issue...
Looks to me like I(7) is the probe, an absolute, and changing the number is a hard function change, so you don't really treat "I" like a variable in the sense of assigning a changing value.
Me thinks an If-Then GoTo statement should work, but the TURNONPROBE is where the I(7) would be invoked....
Neil?????