Failed to convert parameter value from a Label to a Int32.

hi, how to solve this?
here, i give coding. i am getting error like failed to convert parameter value from a Label to a Int32, when debegger excutes on ExcuteNonQuery();
protected void utnclcicked(object sender, ImageClickEventArgs e) { for (int i = 0; i <= C1GridView1.Rows.Count-1; i++) { TextBox tqty1 = (TextBox)C1GridView1.Rows[i].Cells[7].FindControl("num"); TextBox l1= (TextBox)GridView1.Rows[i].Cells[0].FindControl("txtnote"); Label m1= (Label)GridView1.Rows[i].Cells[1].FindControl("lblmaxqty"); Label m2= (Label)GridView1.Rows[i].Cells[2].FindControl("lblminqty"); Label m3= (Label)GridView1.Rows[i].Cells[3].FindControl("lblivtfid"); Label m4= (Label)GridView1.Rows[i].Cells[4].FindControl("code"); Label m5= (Label)GridView1.Rows[i].Cells[6].FindControl("descript"); Label m6= (Label)GridView1.Rows[i].Cells[8]. ...