How to increase count on variable
Solution 1:
You are specifically setting myUpDownCnt as a local variable, value 0 at the beginning of each idle function entry.
Instead make it a a global, outside your function, so you only define it once.
global myUpDownCnt -- declare myUpDownCnt
set myUpDownCnt to 0 -- initialize myUpDownCnt
on function ()
set myUpDownCnt to (myUpDownCnt + 1)
end function