dtSearchNetApi4.dll requires the MFC and CRT components included with Visual Studio 2010 Service Pack 1. To install these components, you can use Microsoft redistributable installers vcredist_x86.exe and vcredist_x64.exe that are available from these links: 

Microsoft Visual C++ 2010 SP1 Redistributable Package (x86) 

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=c32f406a-f8fc-4164-b6eb-5328b8578f03 

Microsoft Visual C++ 2010 SP1 Redistributable Package (x64) 

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=C68CCBB6-75EF-4C9D-A326-879EAB4FCDF8 

vcredist_x86.exe is required for 32-bit applications. 

vcredist_x64.exe is required for 64-bit applications.

dtSearchNetApi2.dll requires the MFC and CRT components included with Visual Studio 2005. To install these components, you can use Microsoft redistributable installers vcredist_x86.exe and vcredist_x64.exe that are available from this link: 

Microsoft Visual C++ 2005 Service Pack 1 Redistributable Package MFC Security Update (June 7, 2011) 

http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=26347 

vcredist_x86.exe is required for 32-bit applications. 

vcredist_x64.exe is required for 64-bit applications. 

There have been several versions of vcredist_x86.exe and vcredist_x64.exe as they have been updated for service packs and security patches since 2005. Use of older versions with the current version of the dtSearch .NET API will result in an "application configuration is incorrect" exception when you try to run your application.

Unfortunately there is no way in Visual Studio to build dtSearchNetApi2.dll so it does not depend on the MFC and CRT DLLs. Because it is a mixed-mode DLL (so it can interface with both .NET and the dtSearch Engine's C++ API), it has to dynamically link both the MFC and CRT DLLs.

dtSearchNetApi.dll, the dtSearch .NET API for Visual Studio 2003 only, requires MSVCR71.dll, which is included with Visual Studio .NET 2003.

Installing the dtSearch Engine