My gridview does not display.

I am creating a web part on SharePoint that shows site owners and their email addresses. I am able to show that information in a listbox, but I would rather do it in a gridview. When I change my code to display the info in a gridview, the gridview does not display.

Here is the code I have:

namespace DisplaySiteOwnersVWP.VisualWebPart1
{
[ToolboxItemAttribute(false)]
public partial class VisualWebPart1 : WebPart
{

    string mySiteURL = "my Site URL goes here";
    DataTable dtTable = new DataTable();


    public VisualWebPart1()
    {
    }


    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);
        InitializeControl();
    }


    protected void Page_Load(object sender, EventArgs e)
    {

        dtTable.Columns.Add("Name");
        dtTable.Columns.Add("Email");

        using (SPSite site = new SPSite(mySiteURL))
        {
            using (SPWeb web = site.RootWeb)
            {
                SPGroup ownerGroup = web.AssociatedOwnerGroup;

                if (ownerGroup != null)
                {
                    foreach (SPUser user in ownerGroup.Users)
                    {
                        if (user.IsSiteAdmin == true)
                        {
                            DataRow dtRow = dtTable.NewRow();
                            dtRow["Name"] = user.Name;
                            dtRow["Email"] = user.Email;
                        }
                    }
                }

                gvOwners.DataSource = dtTable;
                gvOwners.DataBind();

            }
        }

    } } }