Hallo Thomas!
wow - many, many, ... thanks ;) - now it is working ...
the problem is that in the last line you are creating a new instance of the PDxmlrpc class, although you want to output data over the one you created with the pyext object (which represents a PD external). You'd rather have to store and use a reference to your existing object, like in the following.
okay - I understand ... thanks
LG Georg