When you get an error like this
A procedure couldn’t be found in library Addons\SItoA\Application\bin\nt-x86-64\sitoa.dll. The library will not be loaded.
it usually doesn’t mean that Softimage couldn’t find the DLL (sitoa.dll in this case).
Typically, this error is caused by a missing DLL dependency, or the wrong version of a dependent DLL. You can use Dependency Walker and Process Monitor to track down what’s going wrong. A “DLL dependency” or “dependent DLL” is another file that sitoa.dll depends on. When Softimage loads sitoa.dll, that other DLL isn’t found, or if it is, it’s the wrong version. And so you get the error.
eX-SI 
Might have something to do with the obscure folder Softimage is looking in: “nt-x86-65”. 😀
Ah yes 🙂
In the actual case, the problem was another version of a DLL that Arnold uses. I never got the details, but I would guess it was a conflicting version of either OpenImageIO.dll or tbb.dll.
A typical dependency issue I notice on the forums is the missing Visual C++ redistributable. Developers fail to mention it, because they simply do not notice (having the VC Tools installed themselves) that this could be an issue. I foresee a new wave of those kind of reports once the development community start using the Visual C++ 2012 tools… 😉
PS You might want to consider “unsticking” the “Installing Softimage 2013” topic and make the “A new beginning…” your new opening sticky…
😉
That’s a good idea and I did it.
I was thinking of unsticking the Installing post the other day.