Add attributes to Entity Framework database first generated classes

I am using Entity Framework 4.1 and generating my classes using the database first approach. I have a an EDMX file in my solution.

I am trying to add attributes to my classes using the MetadataTypeAttribute approach which seems to be the recommended way of doing this outside of editing the T4 template, however, I cannot seem to get it to work because I keep getting this compile error:

'Patient' is an ambiguous reference between 'PatientManagementSystem.Patient' and 'PatientManagementSystem.Models.Patient'

Here is the code I am using:

[MetadataTypeAttribute(typeof(PatientMetadata))]
public partial class Patient
{
}

public class PatientMetadata
{

    [Required]
    public string LastName {get; set;}

}

Is this error happening because I don't actually have classes for this because I am doing Database first and everything in the EDMX?

Thanks! Flea