Back with MSFX - with a problem

I'm back flying MSFX after an extensive layoff, mostly due to a major back op. I did pick up a problem, probably due to cobwebs in my upperstory. I can't engage higher simulator rates (Pressing R om my keyboard). I tried errasing and reapplying R and even allocating NUM + but to no avail. All other keyboard commands that I tried, worked perfectly. Can somebody please advise??