FIlter expression not working Sqldatasource

This is my sqldatasource with filter expression

   <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
                    ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
                    SelectCommand="SELECT [id], [title], [client], [projectmanager], [project_scope], [project_materials], [project_gating], [project_cavities], [project_fil开发者_如何学Ce], [project_otherdetails], [priority], [commodity], [status], [start_date], [end_date] FROM [project_details]" 
                    ProviderName="<%$ ConnectionStrings:ConnectionString.ProviderName %>" 
                    EnableCaching="True" CacheDuration="1000" 
FilterExpression="title= '{2}'">



 <FilterParameters>
                    <asp:ControlParameter ControlID="DropDownList1" Name="mainsearch" 
                        PropertyName="SelectedItem.Value" />
                    <asp:ControlParameter ControlID="TextBox2" Name="start_date" 
                        PropertyName="Text" />
                    <asp:ControlParameter ControlID="TextBox3" Name="end_date" 
                        PropertyName="Text" />
    <asp:ControlParameter   

                                  </FilterParameters>



    </asp:SqlDataSource>

when i enter the value in Textbox2 it is not working what might be the problem

Because you set the ControlID="TextBox1" in your SQL DataSource SelectParameters, but you are setting the value in Textbox2. You have to change it to <asp:ControlParameter ControlID="TextBox2"

<asp:ControlParameter ControlID="TextBox2" DefaultValue="%" Name="title" 
            PropertyName="Text" Type="String" />

Edit: Following your comments, you want to clear the Where Clause. You can do like...

protected void SqlDataSource1_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
{
    SqlDataSource1.SelectParameters.Clear(); // First Clear the Selected parameters
    SqlDataSource1.SelectCommand = "SELECT [id], [title], [client], [projectmanager], [project_scope], [project_materials], [project_gating], [project_cavities], [project_file], [project_otherdetails], [priority], [commodity], [status], [start_date], [end_date] FROM [project_details]";
}