client side validation in asp.net using javascript

Question

client side validation in asp.net using javascript OnClientClick function notworking

 

<asp:Button ID="Btn_Insert" runat="server" Text="Insert" BackColor="#333333" BorderColor="#004000" BorderStyle="Solid" Font-Bold="True" Font-Italic="True" Font-Size="Large" ForeColor="#FFFFCC" Width="60px" OnClientClick="Btn_Insert_Click1" />

 

after submit buttion:

error:

one textbox in text clear automatically will not check  code also

Onclick function is working properly but requierment client validation