Error / Bug: rtt/tests/ types_test fails with AType assignment

I test the behaviour of own struct data types with rtt/tests/types_test.cpp. I extended in BOOST_AUTO_TEST_CASE( testTypes ) the following:
In the beginning:
Types()->addType( new StructTypeInfo<AType,false>("astruct"));
Extension of string test:
"var astruct aVar\n" +
"var astruct bVar\n" +
"aVar.a = 42\n" +
"do test.assertMsg(aVar.a == 42, \"aVar.a != 42 assignement failed - testTypes\")\n" +
"bVar = aVar\n" +
"do test.assertMsg(bVar.a == 42, \"aVar.a != 42 assignement failed - testTypes\")\n" +

Cmtest -R testTypes fails in the second assertion. So the assignment operator doesn't work with own struct types. Any suggestions how I can fix this problem?