Can't populate listbox

Question

Here's the relevant C#:

List<string> emailChoices = new List<string>();

string emailPermissionsTable = "EmailPermissions";
sqlConn.ConnectionString = sqlConnStr;
sqlConn.Open();
sqlComm.Connection = sqlConn;
sqlComm.CommandText = "SELECT * FROM " + emailPermissionsTable + " WHERE Username = '" + user + "';";
sqlDr = sqlComm.ExecuteReader();

emailChoices.Clear();
while (sqlDr.Read())
{
    string emailAddy = sqlDr["EmailRecipient"].ToString();
    emailChoices.Add(emailAddy);
}

emailListBox.DataSource = emailChoices;
emailListBox.DataBind();

... and the relevant code-behind:

<asp:ListBox ID="emailListBox" Width="200px" runat="server"></asp:ListBox>

I can verify that the emailChoices list is being populated correctly.  Why aren't the list elements showing up in the listbox?  What have I missed?  (Even if I look at the page source, it doesn't seem that the list is being loaded.)