ASP.Net GridView Error: Conversion from string '' to type Date is not valid

Thank you for help

I have label on form I display date on it

I try display this label in gridview but every time the column appears

Empty

here is my code :

<asp:TemplateField HeaderText="التاريخ">
    <ItemTemplate>
        <asp:Label ID="txtdats" runat="server" Text="<% #Label4.Text  %>" >  </asp:Label>
    </ItemTemplate>
</asp:TemplateField>

And i tried another codes like :

Text="<% #CDate(Label4.Text) %>" > and error appears

Conversion from string "" to type 'Date' is not valid.'