Why am I not able to use 32-bit DLL COM Objects in 64-bit MATLAB?

I can instantiate a 32-bit COM DLL-file as an In-Process (InProc) ActiveX Server in 32-bit MATLAB:

a = actxserver('MSOSOAP.HttpConnector30')
a = 

COM.MSOSOAP_HttpConnector30

However, when I attempt the same in 64-bit MATLAB:

b = actxserver('MSOSOAP.HttpConnector30')

I receive the following error:

ERROR: ??? Server Creation Failed: Class not registered

Answer 1

[MathWorks Support Team]

The documentation for MATLAB 7.6 (R2008a) has been updated to incorporate the relevant information. This information can be accessed under the section 'Instantiating a DLL component':

https://www.mathworks.com/help/matlab/matlab_external/creating-com-objects.html

For previous product releases, read below for any possible workarounds:

Microsoft does not support loading 32-bit DLLs or In-Process (InProc) COM Servers into a 64-bit application, or vice-versa. For additional information, please refer to the following resource on MSDN:

https://docs.microsoft.com/en-us/windows/win32/winprog64/process-interoperability

This limitation does not apply to COM Automation servers that are EXE-files (e.g. Excel, 32-bit MATLAB etc.). These servers will work as expected.