Here is the crux of the problem. All 6 modes (0 thru 5) of your indicator are permanently stuck at a value of either 0 or 2147483647 (empty) and never change. Kinda hard to build conditions, heh? Between all the variables, empty values, and conditions in this indi's code; I can't figure out why. Frankly, I have no idea how it draws lines at all.
Sooooo... I looked for a workaround. In the existing code the alert variables default to false, which translates to a value of 0 in MT4. When a signal triggers they change to true, or 1 in MT4. I verifed this via temporarily adding print commands to the code. So I copied the 2 alert variables (basically, buy and sell) from the code and added them as 2 new indicator modes (6 and 7, respectively). They are basically ghost modes.
Ideally
... Mode 6 = 1, then BUY; Mode 7 = 1, then SELL. I'm well beyond my capabilities here, so I'll be almost as happy as you if this works.