private void Change_Students_Click(object sender, EventArgs e)
        {
            string value = "";

            if (txtValue.Text == "")
            {
                MessageBox.Show("The value can't be nothing");
                return;
            }
            if (!IsInt(txtValue.Text))
            {
                MessageBox.Show("Not a valid value(Only number, No comma's)");
                return;
            }
            try
            {
                value = txtValue.Text;
                ListViewItem item = listViewActivity.SelectedItems[0];
                SomerenLogic.Activity_Service activity_Service = new Activity_Service();
                activity_Service.UpdateStudent(value, int.Parse(item.Text));
            }
            catch (ArgumentOutOfRangeException)
            {
                MessageBox.Show("Select an Item");
                return;
            }

            showPanel("Activity");
        }