c# anp.net grid view

Question

Hello
I am having issues displaying vertical lines between the columns in my grid view. I have tried few suggestions that I have found online however none of them worked for me. Your help solving this issue would be appreciated. My code is attached below. Thank you.

<asp:GridView ID="gridVw1" runat="server" PageSize="20" AutoGenerateColumns="False" GridLines="Both" BorderColor="Black" BorderWidth="1px" BorderStyle="Solid" >
   <Columns>
     <asp:TemplateField HeaderText="Img">
          <ItemTemplate >
                  <asp:ImageButton ID="gridBtnImg" runat="server" ImageUrl ='<%# Eval("Path") %>'  height="18px" Width="18px" ItemStyle-HorizontalAlign="Center" ItemStyle-VerticalAlign="Center"/>
          </ItemTemplate>
      </asp:TemplateField> 
      <asp:BoundField DataField="Name" HeaderText="Name" ReadOnly="True" ItemStyle-HorizontalAlign="Center"/>
  </Columns>
  <AlternatingRowStyle BackColor="#E2E2E2" BorderStyle="Solid" BorderColor="Black"  BorderWidth="1px"/>
  <FooterStyle BackColor="Black"/>
  <HeaderStyle BackColor="#D6D6D6" ForeColor ="Black" Height="6px" HorizontalAlign="Center" VerticalAlign="Middle" Font-Names="Calibri" Font-Size="Medium" BorderStyle="Solid"  BorderColor="#999999" BorderWidth="1px"/>
  <RowStyle BackColor="White" Font-Names="Calibri" Font-Size="Medium" BorderStyle="Solid" BorderColor="Black" BorderWidth="1px"/>
</asp:GridView>