title: Regular expression error message
body: <p>Using the <code>RegularExpression(@"^\d{1,15}$")]</code>, I want the user to enter digits up to 15 in length, which returns the error message <em>'Please enter up to 15 digits for a contact number'</em> if this is not correct</p>
  
  <pre><code>[Required(ErrorMessage = ("Please enter up to 15 digits for a contact number")), Display(Name = "Contact Number"), RegularExpression(@"^\d{1,15}$")]
  public string ContactNumber { get; set; }
  </code></pre>
  
  <p>If the user fails to do this I am left with the error message:</p>
  
  <pre><code>The field Contact Number must match the regular expression '^\d{1,15}$'.
  </code></pre>
  
  <p>instead of <code>'Please enter up to 15 digits for a contact number'</code>...does anyone know why?
  thanks</p>