AFAIK, the pinouts for the serial modes can change from mouse to mouse, brand to brand. Check to see if your connector and your mouse have identical pinouts.

I believe that the logitech and ms pinouts were different. I don't know if it would help much if you specifically seek a MS adapter, given that most vendors are probably clueless, vs just hitting up thrift stores etc and trying what you find.

Another thing that can bite you in the arse with onboard i/o and I/O cards that didn't come with serial on the backplate... is that you might not have got the right serial headers... there's at least 3 ways they are wired up, so random headers might not be what's needed on given mobo or I/O card.

IMO, for nearly all legacy computing needs, an RS-232 serial mouse is all you ever need unless you are one of the weird people who can't use ball mice. An RS-232 mouse will work on all systems from the 5150 to probably even a few modern boards with an RS-232 header (I mean you could always use an RS-232 card).

PS/2 mice are cool, but I honestly do not seek them out all that much as they aren't has useful as serial mice. My main serial mouse is a NOS Mitsumi serial mouse that I bought (and indeed repaired) off EBay. It works with my 486, P3, and will work with any serial compatible machine. Heck, if you had the drivers you could use this on non-PCs in theory.