I am writing a C# program that interface with COM object through COM interop.
I have a third-party program that register itself as the COM server when I execute the Application. This works fine in 32-bit Windows Vista and I can interface with the interop just fine. (The reference show up in "COM" tab from Visual Studio when you click "Add Reference")
However, the reference does not show up in "COM" tab on my 64-bit Windows 7 machine after I execute the application. Any thoughts, why would this happen? I actually tried using regsvr32.exe to register the application manually but it didn't work either (error message saying "entry-point DllRegisterServer was not found)
Best Answer
You are not going to be able to use it as long as it doesn't show up in the COM tab. The regsvr32.exe utility is for DLLs, this however sounds like an EXE. If it is a DLL then it needs to be registered with the 32-bit version of regsvr32.exe, the one in c:\windows\syswow64. If it is an EXE then the normal way to get it to register itself is by running it with the /regserver command line option.
Additionally, if this is a DLL or an EXE for which you don't have a 64-bit proxy/stub then you'll have to force your app to run in 32-bit mode. Project + Properties, Build tab, Platform Target = x86.
If all else fails, you really do need support from the vendor of this program. Surely they'll have an update available that is verified to work properly on 64-bit operating systems. If they are no longer around, running this in a virtual machine is always a possibility.