While doing some of my projects i encountered this error.
It happens mostly because some of dlls used in .net application are missing are or built with one configuration and your project is built with another configuration.
One of the solution is to download
and to check the dll that is giving the error for dependencies..if some of the dependencies are missing add them to right path.
Another problem is that if you are using dll that is built for ex for 32 bit system and you are building your project with Any CPU this wont work on 64 bit systems.
You have to build your project also for X86 architecture so you can use that 32 bit dll normally in your project.
You can set the architecture for you project for specific architecture in VISUAL Studio .NET like this:
Right Click on Solution -> Properties -> Configuration Properties -> Configuration Manager
If you dont have for ex X86 architecture go to Configuration Manager , click on Platform and select New.
You can then choose which platform you want to create.