Have you downloaded and installed AutoCAD 2014 yet? If you did, you will notice a new set of security features in AutoCAD that will not let you load custom applications that are not in a secure, trusted path. This behavior is controlled with SECURELOAD and TRUSTEDPATHS settings.
The easiest and best way to deploy your apps is to install your applications as Application bundles as the bundle paths are automatically treated as trusted paths. Check out this Autodesk Autoloader white paper for detailed information on its technology.
If this is not an option for you, you could try digitally signing your application. For this you will need a digital certificate from a well know certificate authority. AutoCAD 2014 will load digitally signed applications even if they are not in a trusted path.
One note for .NET developers. Digitally signing your application is different from strong naming your applications. Here is a very informative FAQ on the differences.