@tosch you are shure that .1.3.6.1.4.1.9.1 is the correct OID to check? After a qiuck look in the check files it looks like the content of .1.3.6.1.2.1.1.2.0 (sysObjectID) is the importent part for the check to discover a WLC.
@ercole77 can you check this OID please?