to design mapimport method

[ravendra]

hi
I need to import dgn(Microstation design) into autocad
courently i try with following code but its throw the error means not initializing

AcMapIEImporter* importer = AcMapImporter();
AcMapIE::ErrCode ec = importer->Init("MicroStation Design", s.c_str());

Error is : kErr_Invalid

Please suggesst me the best way to import the dgn to dwg with their object data