OS9: problematic talking to OSX

I seem to be unable to make any reference or call from OS 9 to any remotely running OS X program. Program linking is activated on the OS X machine. On the OS9 machine, I can see, mount and acces OSX volumes via AppleTalk. There is no error message of a non-existing server or any or its processes - just no response…
I am NOT using the “talk as user” call (Akua OSAX) as it is unavailable or crashes since OS9.
Anybody any clue…?
Eelco Houwink