What I found is that sometimes it is then enough to use this routine in tMap by CTRL + Space choosing the right routine. Somehow it doesn't work always. What helps then is to add "routines."
Example: fuzzyMatching.getLevenshteinDistance( string1,string2) ist what CTRL + Spaces enters. I need to extend it to : routines.fuzzyMatching.getLevenshteinDistance( string1,string2)
Looks to me like a bug as it is not always necessary.