It looks like your assembly/DLL is failing to load.
You can debug this using the Microsoft Fusion Log Viewer utility, i.e. fuslogvw. Run the utility from the Visual Studio Command Prompt. Make sure to set a Custom Log Location and set it to a directory which exists. What you want to see is binds that fail. The way that assemblies are located in .NET is complex:(
If this is too much, then try to use the free Reflector utility from Red-Gate. What you want to do is to expand the dependencies in order to find those that have load issues. In the unmanaged world this was done using the Depends utility.