Jürgen, If you had SR13 installed when compiling your plug-in, than that one will be required for others to run it. The problem with SR13 (second version) is that changes were not deemed to be important enough to trigger an auto-update and as such many will only have SR12 installed. I suppose it would be best to compile it against SR12.
As another such example, see:
By the way, do you have a manual for Concha - or an example file or so?