ArgumentError: Error #2004: One of the parameters is invalid.

I hope this will help you out there before you spend too many hours on this one.

Issue that caused the error:
Making a remote call using a RemoteObject that returns back a strongly typed object. The call is made and the Error is triggered before you can capture it in the debugger. I thought I was losing my mind. Everything is exactly the way I have done remote calls a hundred times.

remoteObject.SomeMethod();
SomeMethod() returns a strongly typed class object.

Solution and reason for the error:
Make sure you have an instance of the object referenced in your project. The object is not linked into your .swf upon compiling the project, because there is not a reference to the object anywhere in the project, so the RemoteObject call cannot find the class. What a simple solution, but what a non descriptive error. Now that I read the error it makes a little more sense.