I think I should qualify this to avoid fixing the symptom and not the problem.

I'm using this line as part of a function to check whether a file is open or not. If it's open, I want to activate it. If it's not open, I want to open it.

Both file path and name include spaces and there is no drive mapped (so I'm using relative pathes).

Any solution will do me, but understanding how to work around the "space issue" (assuming it is a true issue) would arm me for the future.