autocomplete functionality not working on a textbox

See more:

C#

i am trying to add a autocomplete fuctionality in my desktop application project..

i have a textbox for perscription

but i am not getting autocomplete functionility in textbox .

i don't know y.


here is the code. i put that in form load event

AutoCompleteStringCollection namesCollection = new AutoCompleteStringCollection();

            OleDbDataReader dReader; 
            OleDbConnection conn = new OleDbConnection(); 
            conn.ConnectionString = connectionString; 
            OleDbCommand cmd = new OleDbCommand(); 
            cmd.Connection = conn; 
           cmd.CommandType = CommandType.Text;
            
           cmd.CommandText = "Select [MedicineName] from [medicines] order by [MedicineName] asc"; 
            conn.Open(); 
            dReader = cmd.ExecuteReader();
            if (dReader.HasRows == true) 
            { 
                while (dReader.Read())   
                namesCollection.Add(dReader["MedicineName"].ToString()); 
            }
            else 
            { 
                MessageBox.Show("Data not found"); 
            } 
            dReader.Close();
           
            txtperscription.AutoCompleteMode = AutoCompleteMode.Suggest;
            
            txtperscription.AutoCompleteSource = AutoCompleteSource.CustomSource;

            txtperscription.AutoCompleteCustomSource = namesCollection;