On windows server 2008 R2.
Make sure the appPool is set to 32 bit mode and install the
Microsoft Visual C++ 2010 Redistributable Package (x86)
I had installed the 2010 64 bit and the 2012 64 and x86, but still had the problem. I needed the C++ 2010 redist x86.
In this case I’m using the Chilkat 32 bit .net 40 dll.