I am using xVal to validate my forms in asp.net MVC 1.0

Not sure why my regular expression isn't validating correctly.

It validates with the value of "12345" It validates with the value of "12345 " It validates with the value of "12345 -" It validates with the value of "12345 -1" It validates with the value of "12345 -12" ... etc

For a zip code I expect one of the two patterns:

12345 or 12345 -1234

Here are the two regex I tried:

(\d{5})((( -)(\d{4}))?)

(\d{5})|(\d{5} -\d{4})

Here is my MetaData class for xVal

[MetadataType(typeof(TIDServiceMetadata))]
public class TIDServiceStep : TIDDetail
{
   public class TIDServiceMetadata
   {
       [Required(ErrorMessage = " [Required] ")]
       [RegularExpression(@"(\d{5})|(\d{5} -\d{4})", ErrorMessage = " Invalid Zip ")]
       public string Zip { get; set; }
   }
}

Here is my aspx page:

<% Html.BeginForm("Edit", "Profile", FormMethod.Post); %>
<table border="0" cellpadding="0" cellspacing="0">
<tr>
   <td>
      <h6>Zip:</h6>
   </td>
   <td>
      <%= Html.TextBox("Profile.Zip")%>
   </td>
</tr>
<tr>
   <td>
      <input type="submit"/>
   </td> 
</tr>
</table>
<% Html.EndForm(); %>

<% Html.Telerik().ScriptRegistrar()
        .OnDocumentReady(() =>
   { %>
   <%= Html.ClientSideValidation<TIDProfileStep>("Profile").SuppressScriptTags() %>
<% }); %>