error : using checkboklist in gridview

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C#

ASP.NET

Dear all,

I want To insert data in database using checkboxlist in gridview

by check the data i want to insert from checkboxlist foreach row

the Error :
data insert one row only every time i click on Submit button

i want to insert data for all rows at same time

this is my code

protected void Butaddgang_Click(object sender, EventArgs e)
   {

   inserlaborgangs inlabgang = new inserlaborgangs();

       for (int i = 0; i < GridView1.Rows.Count; i++)
       {
           if (GridView1.Rows[i].RowType == DataControlRowType.DataRow)
           {


               int labfilenoo = (int)GridView1.DataKeys[i].Value;
               CheckBoxList gang = (CheckBoxList)GridView1.Rows[i].FindControl("RadioButtongang");

               TextBox remarks = (TextBox)GridView1.Rows[i].FindControl("Textremarks");

               // add parameters
               inlabgang.labfileno = labfilenoo;
               inlabgang.Remarks = remarks.Text;



               if (gang.SelectedIndex > -1)
               {

                   inlabgang.gangid = int.Parse(gang.SelectedValue.ToString());
                   inlabgang.formanid = 0;
                   inlabgang.Add();
                   inlab.Update();

                   LblMsg.Text = "Done";
                   Page.DataBind();

               }





           }


       }