I am trying to load the PlcHandlerDll.dll by ironPython: import clr clr.AddReference("PLCHandlerDll") I got the following error: System.BadImageFormatException: Could not load file or assembly 'PLCHandler_SDK_Windows_3.5.19.0\bin\Windows\x64\PLCHandlerDll_.dll' or one of its dependencies. The module was expected to contain an assembly manifest. Dose anyone have any suggestion about it? Thanks.