Do you have the software system prerequisites installed on your Windows 11 PC, especially:
- Microsoft .Net Framework 2.0 or later.
- MSXML 4.0 SP2 or later.
- Microsoft Data Access Components (MDAC) 2.6 or later.
Considering that these requirements were formulated some 17 years ago, when software makers used to count on backwards compatibility, it might be wise to try and install the named versions, or else slightly newer versions, on your PC, if possible.
I seem to remember that newer versions of .Net do not always cover all functionality of an older version. And for MSXML the 'or later' could just refer to the SP2 (service pack 2), while version 4.0 is required...
(Note that Mathcad 15 required: "MSXML 4.0 SP2 Parser and SDK (this exact version of MSXML is required)".)
Success!
Luc