Public Transport and Shortest Path Tree

is public transport not supported by the shortest path tree analysis?
I builded a graph with a foot an pt profile. Isocrones are generated for both profiles (http://localhost:8989/isochrone?profile=foot/pt…), the shortest path tree point-csv ist generated for the foot profile (http://localhost:8989/spt?profile=foot&point=…) but the pt profile (http://localhost:8989/spt?profile=pt&point=…) returns an error: “The requested profile ‘pt’ does not exist”
Thank You!