Date validation

<asp:TextBox ID="txtVisitDate" TabIndex="1" Width="100px" MaxLength="10" runat="server"

CssClass="special_text_brown"></asp:TextBox>

<asp:RegularExpressionValidator runat="server" ID="regVisitDate" ControlToValidate="txtVisitDate"

ErrorMessage="Please enter valid date" Display="Dynamic" ValidationExpression="(((0?[1-9]|1[012])/(0?[1-9]|1\d|2[0-8])|(0?[13456789]|1[012])/(29|30)|(0?[13578]|1[02])/31)/(19|[2-9]\d)\d{2}|0?2/29/((19|[2-9]\d)(0[48]|[2468][048]|[13579][26])|(([2468][048]|[3579][26])00)))" />

<cc1:FilteredTextBoxExtender ID="ftxtVisitDate" runat="server" TargetControlID="txtVisitDate"

FilterType="Custom" InvalidChars="A-Z, a-z" ValidChars="/,1,2,3,4,5,6,7,8,9,0">

</cc1:FilteredTextBoxExtender>

<asp:ValidationSummary ID="ValidationSummary1" runat="server" ShowMessageBox="false"

ShowSummary="false" />

<cc1:CalendarExtender ID="calextVisitdate" Format="MM/dd/yyyy" TargetControlID="txtVisitDate"

runat="server">

</cc1:CalendarExtender>