MVC :: System.MissingMethodException: No Parameterless Constructor Defined For This Object - How To Fix This Error

I've set up a strongly-typed View and a controller method to save the object represented in that View. The object in question is from a class that uses named parameters with default values. This is not a database object, but rather is the intermediate object that is used for the display and user input. It gets translated into a database object in the service class. Anyway, when I attempt to save the object, I get the following error:

System.MissingMethodException: No parameterless constructor defined for this object.

This is kind of aggravating. I can add a parameterless constructor to the class, and then everything works just fine. I just don't understand why it is necessary. I'm new to named parameters with default values, but the reading and such that I've done has described that method calls with default values do not have to have a 'no-parameter' implementation. You can just call the method with any or none of the parameters specified and everything works as expected. If there is a 'no-parameter' implementation and no params are passed, then that one is used, since it is more specific than the one with default values. Is the behavior somehow different when this is used in the constructor of a class? Why would I have to include a parameterless constructor when I have all the values accounted for? Is the runtime creating an object on the fly as the save method executes, which requires this? The method is like this:

[Code]....

I'm wondering if the object is instantiated by the runtime in order to populate the method parameter, and then assigned values from the form collection. I suppose that would make sense, but I do not understand why this causes an exception. For what reason would a parameterless constructor be required?