Validating more than one field with Fool Proof : <p>Hello I'm using MVC <a href="http://foolproof.codeplex.com/" rel="nofollow noreferrer"><strong>Fool Proof Validation.</strong></a> to validate my model, and i need to use <code>RequiredIfNotEmpty</code> with two fields but i'm getting issues with it</p>

<p><strong>Model</strong></p>

<pre><code>public class Conexionado{

    [DisplayName("Conexión")]
    [RequiredIfNotEmpty("Conex_BT2_Pos", ErrorMessage = "Error!")]
    [RequiredIfNotEmpty("Conex_BT2_N", ErrorMessage = "Conex_BT2 Cant be empty if Conex_BT2_N isnt!")]
    public string Conex_BT2 { get; set; }

    public string Conex_BT2_N { get; set; }

    [DisplayName("Ángulo BT")]
    [Range(0, 11, ErrorMessage = "Incorrect number")]
    public int? Conex_BT2_Pos { get; set; }

}
</code></pre>

<p>I have tried some like </p>

<pre><code>[RequiredIfNotEmpty("Conex_BT2_Pos , Conex_BT2_N", ErrorMessage = "Error!")]

[RequiredIfNotEmpty("Conex_BT2_Pos || Conex_BT2_N", ErrorMessage = "Error!")]
</code></pre>

<p>But in this case, i can compile, but when i try to use <code>Conex_BT2</code> i get</p>

<blockquote>
  <p>'System.NullReferenceException' en FoolproofValidation.dll</p>
</blockquote>

<p>Someone know how i must deal with it?</p>

<p>Thanks!</p>
