Display name in Data Entity framework - asp.net-mvc

Question

I'd like to know how to change the display name of a model, and customize error messages in Entity Framework. I tried the following but it didn't work.
[Required(ErrorMessage = "Required .... :")]
[Display(Name = "Name Agency : ")]
[EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=false)]
[DataMemberAttribute()]
public global::System.String Nag
{
get
{
//code
}
set
{
//code
}
}
This is the code behind my form that adds data into my database. I've omitted irrelevant lines.
<% using (Html.BeginForm("addcar", "Agence", FormMethod.Post, new { #class = "search_form" }))
{ %>
<%: Html.ValidationSummary(true) %>
<div class="editor-label">
<%: Html.LabelFor(model => model.Dmcv) %>
</div>
<div class="editor-field">
<%: Html.EditorFor(model => model.Dmcv) %>
<%: Html.ValidationMessageFor(model => model.Dmcv) %>
</div>
<div class="editor-label">
<%: Html.LabelFor(model => model.Puisv) %>
</div>
<div class="editor-field">
<%: Html.EditorFor(model => model.Puisv) %>
<%: Html.ValidationMessageFor(model => model.Puisv) %>
</div>
// Similaire code
<p>
<input type="submit" value="Create" />
</p>
<% } %>

Answer 1

Change [Display(Name = "Name Agency")] to [DisplayName("Name Agency")] instead.

Answer 2

First you need to reference this:
using System.ComponentModel.DataAnnotations;
For changing the display name of the column, actually [Display(Name="Name Agency")] is OK. I'm using it in my projects.
For error message
[Required(ErrorMessage="Required...")]
I read that it is possible that this won't work if you are using the entity framework designer because the designer overwrites your changes over and over then you will need to use the metadatatype something like this:
[MetadataType(typeof(MetadataMyClass))]
public partial class myclass
{
}
//data annotations here
public class MetadataMyClass
{
[Required(ErrorMessage = "Required...")]
[Display(Name="Column Name")]
public global:: System.String Nag
{
// ... etc, etc...
}
}