I don't really know where to look for an error... the situation: I have an ASPX view which contains a form and a few input's, and when I click the submit button everything is POST'ed to one of my ASP.NET MVC actions.

When I set a breakpoint there, it is hit correctly. When I use FireBug to see what is sent to the action, I correctly see data1=abc&data2=something&data3=1234. 

However, nothing is arriving in my action method. ViewData is empty, there is no ViewData["data1"] or anything else that would show that data arrived.

How can this be? Where can I start looking for the error?