RegularExpression PAN Validation

<asp:TextBox ID="txt_PanNo" runat="server" MaxLength="10"></asp:TextBox>

<asp:RegularExpressionValidator ID="REV_txt_PanNo" runat="server" 
ErrorMessage="Enter valid pan number! " ControlToValidate="txt_PanNo" 
SetFocusOnError="true" ValidationExpression="[A-Z]{5}\d{4}[A-Z]{1}">
</asp:RegularExpressionValidator>
<br/>(case sensitive) eg:-  ASDFG1234C