How to display Checked (Selected) CheckBox rows (data) of GridView in Label in ASP.Net

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C#

ASP.NET

<div style="height: 150px; width: 221px;">
                <input type="text" placeholder="Find" id="txtSearchCompany" style="width: 100%;" class="textboxWidth" />
                <div style="height: 150px; width: 221px; overflow: auto;" class="textboxWidth">
                    <asp:GridView ID="gvCompanyListing" runat="server" AutoGenerateColumns="False" ShowHeader="False" GridLines="None">
                        <Columns>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:CheckBox ID="cbSelect" CssClass="gridCB" runat="server" ItemStyle-Width="10%"  OnCheckedChanged="Select_OnCheckedChanged" AutoPostBack="true" ></asp:CheckBox>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:BoundField DataField="CompanyInfo" SortExpression="CompanyInfo" ItemStyle-Width="92%" ItemStyle-Height="1px"></asp:BoundField>
                        </Columns>
                    </asp:GridView>
                </div>
            </div>
        </div>
        <asp:Label ID="lblmsg" runat="server" />
</div>

this is my aspx page.

And in code behind

protected void Select_OnCheckedChanged(object sender, EventArgs e)
       {
           string name = string.Empty;
           foreach (GridViewRow row in this.gvCompanyListing.Rows)
           {
               CheckBox chkSelect = row.FindControl("cbSelect") as CheckBox;
               if (chkSelect.Checked)
               {
                   name += row.Cells[1].Text + ",";
                   String[] tokens = name.Split(new[] { "," }, StringSplitOptions.RemoveEmptyEntries);
                   this.lblmsg.Text = string.Join("<br />", tokens);
               }
           }

       }

it displays the checked answers correctly,
but on unchecking it remove all the data from label expect the last unchecked option.
(On checking it give 'E,B,C,D' and on unchecking ,the last unchecked options will remain in label)How i will solve my issue.