ASP.NET MVC 3 not accepting my German date format settings - why?

I have a new ASP.NET MVC 3 project, and MVC and Razor are all brand new to me... can't figure this one out.

I have a dev machine on US-English Win7 x64, running English versions of VS 2010 Pro SP1 and ASP.NET MVC 3. But the app I'm working on is for a local client, and needs to be all in German and use all the formatting and defaults 开发者_Go百科commonly used here.

In my view model, I have defined a variable of type DateTime and augmented it with some extra hints as to how to display (and edit) it - I need the Swiss-German date formatting, which is: day.month.year (in that order, separated by dots . - not slashes)

public class MyViewModel
{
    [Display(Name = "Gültig am")]
    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString="dd.MM.yyyy", ApplyFormatInEditMode=true)]
    public DateTime ValidAt { get; set; }
}

(of course, there are more properties in that view model, but those aren't relevant just now)

In my Razor view, I simply use the default stuff set up by the ASP.NET MVC 3 Add View T4 template:

@Html.EditorFor(model => model.ValidAt)

Trouble is: if I enter something like 13.06.2011 (13th of June, 2011) which I believe is valid and conforming to my display and editing formats, I am still getting a client-side validation saying that The value '13.06.2011' is invalid - WHY???

There must be something really fundamental (and probably totally silly) that I'm missing here....

Even though I have set all of this up,

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What do you use for client validation? Did you look at Combining validation methods in jQuery Validation plugin with "or" instead of "and" ?