Strongly typed ViewModel contains unexpected null value

I have a case that is very similar to this, but following the advice in the answers does not solve my problem.

I have a ViewModel in an MVC 2 application that contains another class. I have a controller that contains a strongly typed create method:

[Authorize]
[HttpPost]
public ActionResult Create(AIViewModel ai)
{

}

When I look at the ModelState when I enter the Create method, the data indicates that the simple properties that are present within the AIViewModel class are bound correctly, while the complex type that is in there fails with the following error message:

"The parameter conversion from type 'System.String' to type 'xyz' failed because no type converter can convert between these types."

If I look at the value that it tries to bind, it has indeed the System.String type and value "Create". Anybody has a clue on what I could be doing wrong?

UPDATE: I have found the problem: The property is called Action, which somehow fools the the modelbinder. Renaming t开发者_开发百科he property solved the issue.