I have a XLL mathematical library that I call though Application.Run
in Excel. This is a MAJOR performance bottleneck, and I am trying to
see if I can call it directly though a wrapper instead. I found a
discussion of how to call a XLL as if it were a DLL using xlcall32.dll
on the net, and have compiled this up and put the resulting dll into
the same directory as the XLL.

I then tried to wrap the XLL's function using Private Declare Function
inside Excel. However, this returns an error 53, File Not Found. I
tried adding the complete path to the XLL, but this had no effect.
This leads me to believe the error is misleading, and that it may mean
"dll not registered"?

Question1: Should I be able to use a complete path to find any dll no
matter if they are reged or not?

So then I tried registering the XLL, but this returns "LoadLibrary
failed. GetLastError returns 0x000036b1. According to the very few
hits on the 'net, this too is a completely generic message of dubious
value.

Question 2: Can an XLL be registered? As I understand it, XLL's are a
strict superset of DLLs.

Maury