c# microsoft.Jet.OLEDB.4.0 Zahlen mit Kommas werden nicht eingelesen

        public void ReadCsv(string filename)

        {

            using (OleDbConnection cn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+ filename +";Extended Properties=\"Excel 8.0;HDR=Yes;\";"))

            {

                cn.Open();

                using (OleDbDataAdapter adapter = new OleDbDataAdapter("select *from[PickAndPlace$]", cn))

                {                  

                    DataTable dt = new DataTable("Data");

                    adapter.Fill(dt);

                    dataGridView_MfgData.DataSource = dt; 

                }

            }

        }