Ralf,

You say you are trying to load an instance of a "framework class", but the
tail end of your post indicates that it is a custom class. What class are
you trying to load? Can you post the class declaration (without the full
implementation).

If you want to load the class into another app domain and interact with it
in that appdomain, then it needs to be a pass-by-reference class (derived
from MarshalByRefObject). If you access a serializable object in another app
domain, you will end up with an instance of that object in both app domains.
If the class you need to work with is not pass by reference, then you will
need to create a controller class that is pass-by-reference, instantiate it
in the remote app domain, and use it as an intermediary to manipulate non
pass-by-ref code in the remote app domain.

Re the error you get, I dont know for sure, because I dont know the internal
process that the runtime uses, but I can imagine a situation where the
runtime loads your assembly (because you supply a specific file name), but
when it tries to load assemblies referenced by yours, it cannot find them
because they are not in a location where the runtime searches (probes) by
default.

Regards
Allen