How to Register ActiveX/COM dll in order to use with c#

If the DLL is 32 bit:

Copy the DLL to C:\Windows\SysWoW64\
In an elevated command prompt: %windir%\SysWoW64\regsvr32.exe %windir%\SysWoW64\namedll.dll

if the DLL is 64 bit:

Copy the DLL to C:\Windows\System32\
In an elevated command prompt: %windir%\System32\regsvr32.exe %windir%\System32\namedll.dll

I know it seems the wrong way round, but that's the way it works. See:

http://support.microsoft.com/kb/249873
Quote: "Note On a 64-bit version of a Windows operating system, there are two versions of the Regsv32.exe file:
The 64-bit version is %systemroot%\System32\regsvr32.exe.
The 32-bit version is %systemroot%\SysWoW64\regsvr32.exe.

In order to solve next problem you have to run cmd as an Administrator

“The module “%1″ was loaded but the call to DllRegisterServer failed with error code 0×80004005. For more information about this problem, search online using the error code as a search term”.