ASP.NET - Date formate issue

in Grid view(asp.net,c#)

  <ItemTemplate>
                        <asp:Label ID="lblmodified" runat="server" Text='<%#Convert.ToDateTime(Eval("ModifiedDate")).ToString("dd /MM/ yyyy")%>'></asp:Label>
                      </ItemTemplate>

when it is displaying ----01/01/0001

for that one i wil show simply blank, or message i want to show.

how can i handle this case.

please suggest me.
thanks in advance.

1. Handle the Gridview.Rowdatabound Event
2. In the event find the date textbox.
3.
void CustomersGridView_RowDataBound(Object sender, GridViewRowEventArgs e)
  {

    if(e.Row.RowType == DataControlRowType.DataRow)
    {
    // Display the company name in italics.
    //find the textbox
    TextBox txt=e.row.findcontrol("lblmodified");
    if (txt.text=="v") //if the cell value is 01/01/2026
     {
     txt.text="---"; //Display ---
     
      }

    //e.Row.Cells[1].Text = "<i>" + e.Row.Cells[1].Text + "</i>";

    }

  }

thanks a lot.