cell data not rendering

/*
The resultset rs is well formed and not erroneous. We first create all columns and then add row data to and ObservableList<ObservableList> and finally set it as the data model of the tableview.
*/

 for(int i=0 ; i<rs.getMetaData().getColumnCount(); i++){
                   TableColumn col = new TableColumn(rs.getMetaData().getColumnName(i+1));

                    col.setCellValueFactory(new Callback<CellDataFeatures<TableView,Object>,Object>(){
                                public String call(CellDataFeatures<TableView,Object> param) {
                                int i = param.getIndex();
                                return ((ObservableList)param.getValue()).get(i).toString();
                                }
                             });
                tableview.getColumns().add(col);
                }


                /*
                 * Row data to table
                 */
                while(rs.next()){
                    //Iterate Row
                    ObservableList<Object> row = FXCollections.observableArrayList();
                    for(int i=1 ; i<=rs.getMetaData().getColumnCount(); i++){
                        //Iterate Column
                        row.add(rs.getString(i));
                    }
                    tableData.add(row);
                }

                // Add tableData to tableView
                tableview.setItems(tableData);
          }