at the moment one can't create a material through new MATERIAL(), one has to use mtl_create() as in lite-c, like the other engine objects, these objects have to be created through engine functions!

get the C# wrapper:
for A7.85.4 and A8.30.4, Version 2.3.9
at http://acknexwrapper2.matthias-auer.net/ or visit the thread