Email address RegularExpressionValidator not working properly (VB)

<asp:regularexpressionvalidator id="regEmail" runat="server" controltovalidate="EmailTextBox" ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" display="static" errormessage="Please enter an email address using the format username@domain.com"/> The above control is firing the error message -- even when a valid email address is entered. Any idea what I am doing wrong? Thanks
 
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