DataAnnotations validation (Regular Expression) in asp.net mvc 4 - razor view

The DataAnnotations validator not working in asp.net mvc 4 razor view, when using the special characters in the regular expression.

Model:

[StringLength(100)]
[Display(Description = "First Name")]
[RegularExpression("^([a-zA-Z0-9 .&'-]+)$", ErrorMessage = "Invalid First Name")]
public string FirstName { get; set; }

Razor View:

@Html.TextBoxFor(model => Model.FirstName, new { })
@Html.ValidationMessageFor(model => Model.FirstName)

The unobtrusive validation is rendered in view as:

<input type="text" value="" tabindex="1" style="height:auto;" name="FirstName" maxlength="100" id="FirstName" data-val-regex-pattern="^([a-zA-Z0-9 .&amp;amp;&amp;#39;-]+)$" data-val-regex="Invalid First Name" data-val-length-max="100" data-val-length="The field FirstName must be a string with a maximum length of 100." data-val="true" class="textfield ui-input-text ui-body-d ui-corner-all ui-shadow-inset valid">

The regex pattern in the above html is not rendered as specified in the Model's RegularExpression, which results in error even when entering the valid data (Sam's).

How can i handle this?

--UPDATE--

I have updated the code as per @Rick suggestion

[StringLength(100)]
[Display(Description = "First Name")]
[RegularExpression("([a-zA-Z0-9 .&'-]+)", ErrorMessage = "Enter only alphabets and numbers of First Name")]
public string FirstName { get; set; }

View Source shows the following:

<input data-val="true" data-val-length="The field FirstName must be a string with a maximum length of 100." data-val-length-max="100" data-val-regex="Enter only alphabets and numbers of First Name" data-val-regex-pattern="([a-zA-Z0-9 .&amp;amp;&amp;#39;-]+)" id="FirstName" maxlength="100" name="FirstName" type="text" value="" />

Still i have the same issue.

UPDATE 9 July 2012 - Looks like this is fixed in RTM.

1. We already imply ^ and $ so you don't need to add them. (It doesn't appear to be a problem to include them, but you don't need them)
2. This appears to be a bug in ASP.NET MVC 4/Preview/Beta. I've opened a bug

View source shows the following:

data-val-regex-pattern="([a-zA-Z0-9 .&amp;&#39;-]+)"                  <-- MVC 3
data-val-regex-pattern="([a-zA-Z0-9&#32;.&amp;amp;&amp;#39;-]+)"      <-- MVC 4/Beta

It looks like we're double encoding.

Try escaping those characters:

[RegularExpression(@"^([a-zA-Z0-9 \.\&\'\-]+)$", ErrorMessage = "Invalid First Name")]

Try @ sign at start of expression. So you wont need to type escape characters just copy paste the regular expression in "" and put @ sign. Like so:

[RegularExpression(@"([a-zA-Z\d]+[\w\d]*|)[a-zA-Z]+[\w\d.]*", ErrorMessage = "Invalid username")]
public string Username { get; set; }