mkgmap: add maxspeed to name

I tried to add the maxspeed value to the name, if present. In my lines file, I do:

highway=* & maxspeed=* {set name='${maxspeed}-${name}'; set mkgmap:display_name='${maxspeed}-${mkgmap:display_name}'}

but it does not work: never do I see a maxspeed value before the name (mkgmap version 2724).
Strangely, it works well in the points file, where I add the religion to the name of a place_of_worship by

amenity=place_of_worship & religion=* { set name='${religion}-${name}' }

I am confused now…
How to do it correctly?

Found the source of the problem: “name” has a special rule

(from the Style rules manual of mkgmap).
Because other rules regarding the name were applied before that in my style, that later line had no effect (instead of the expected result of combining the previously set name with the maxspeed value).
I had to change all the previous lines, a lot of copy-paste-code…