missing error message?

[kohlhase]

Typesetting .../courses/uhi/graph-theory/source/sec/crossingnum.de.tex gives me the error message

! LaTeX Error: Unknown message 'unknownnotation' for module 'stex'.

For immediate help type H <return>.
 ...                                              
                                                  
l.11   \setnotation{expectation}{cal}

The problem seems to be the \setnotation in

  \importmodule[smglom/probability]{mod?expectation}
  \setnotation{expectation}{cal}