In my C# web project, a ESLibrary.dll file was included to provide a calculation service. But when I come to this page where the library is called. It always pops error that this dll file cannot found from the path "c:\..\..\ESLibrary.dll". When I check
this file from folder, it is already there.
At last I aware that this library is 32 bit library, but the IIS was run on 64 bit OS. The solution is to enable the 32 bit support in IIS resource pool setting.