override mat. effect id doesn´t work with blend material

[max montana]

i try to get a multimatte render element from objects with a blend material on them, by checking the override material effects id checkbox in the options of material. this works with every material so far, but seems not to with the blend material. i have effect id numbers and checkboxes cklicked in the base material and the coat material. also triesd it without cout, base, etc.
would be nice if someone knows a solution for this