I have version 8.5xx and it is on the disk (well I have loads of versions), I noticed that on my GX Developer V8.5xx it is also greyed out I tried installing it but reports that uninstall is running but it is not. I have GX IEC (2 versions) GX Works 2 & GX Works 3 installed and these have the simulator working. although I do not use it very often. If I start GX Developer session from GX Works 2 then it is there so I assume it must be a different version. Quite baffling.