C# INSERT INTO Access database fails, no errors given

Trying to insert a new record into an MS Access .accdb file. When I run the code below, it appears to work fine. No errors are presented, but nothing updates in the database file either. I have verified that the database is in an accessible location.

selectedNote is an object with the three listed parameters. The only field I'm not including in the query string is the ID field which is autonumber.

string scon = "Provider = Microsoft.ACE.OLEDB.12.0; Data Source = |DataDirectory|AMS.accdb";
string str = "INSERT INTO Notes ([ItemID], [Note], [Note Date]) VALUES (?, ?, ?)";

try
{
    using (OleDbConnection con = new OleDbConnection(scon))
    {
        using (OleDbCommand cmd = new OleDbCommand(str, con))
        {
            cmd.CommandType = CommandType.Text;

            cmd.Parameters.AddWithValue("ItemID", selectedNote.ItemID);
            cmd.Parameters.AddWithValue("Note", selectedNote.Note);
            cmd.Parameters.AddWithValue("Note Date", selectedNote.NoteDate.ToString("dd-MM-yy"));

            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
}
catch (Exception ex)
{
    MessageBox.Show("Failed due to" + ex.Message);
}

Thanks all, hopefully I can get this hammered out.

EDIT: Curiously, I just found that if I hard-code a path to the .accdb file with a line like the following, it actually does write to that file. So I guess the question becomes why is it not working on the build path where the database is in the same path as the exe.

AppDomain.CurrentDomain.SetData("DataDirectory","C:\temp");

I have tried setting DataDirectory to something like AppDomain.CurrentDomain.BaseDirectory, but this doesn't seem to work either.