On many of these old razors that have been lying in drawer for years, bumping into other objects, gathering corrosion, etc... before someone took it, cut some cardboard boxes and decided to put it on Ebay, because it didn't cut boxes that well, it can take a very long time to set a bevel. My personal rule is, that if 10 minutes of work on the Coticule doesn't cut it, I bring out my DMT 600 grit and work on that one till is shaves arm hair. It will do in 10 minutes what can take me an hour on a Coticule.
After the DMT, I do the dulling stroke on glass, once more, and reestablish shaving arm hair level on the Coticule. That should now take less than 3 minutes.
If you don't have a DMT 600 or some other coarse stone in that grit range (please don't put the razor on one of those cheap 220 grit carborundum hones from the tool shop around the corner), you can do it on 600 grit wet&dry sandpaper as well. Beware that the sandpaper doesn't bead up in front of the edge. To prevent that, it's best to stick the sandpaper with some water on a slick and flat surface, like a flooring tile, or something. Stick it near the edge of the tile, so you can use it like a hone.
Don't worry about the previous lack of success. I'm sure it has been good practice for your honing stroke.
Kind regards,
Bart.