Why do I get a .NET SDK exception on my client side even though the item lists successfully? When I look in the log file, I only see this: "File or assembly name vjslib, or one of its dependencies, was not found."
By default, the .NET SDK uses HTTP compression, and you must install the version of Visual J# .NET Redistributable Package that corresponds to your version of the Microsoft .NET Framework on your client. Even if you do not have the J# package, the call will still be made - the request will be send and the response will be received by the application. However, since the package is not available it will not be able to decompress the response and throw an exception. So, even if the your AddItem call is successful, you will still get the exception.
It is always a good idea to use UUID / InvocationID in your AddItem call, so that you do not accidently relist the item in your retries. Please see this knowledge base article UUID: Why, What and How and the documentation for more information on UUID / InvocationID.