Unable to click on child checkbox (without fx:id) in a tablecolumn

I'm trying to click on a child checkbox which is in a tablecolumn (has fx:id) and tableview (has fx:id). The parent checkbox has fx:id which is in the same tablecolumn of child checkbox. Here is my code:

public void clickChild(String id, String yd) throws Exception {
    TableView tableView= (TableView)(fxer.getAt( "#"+id ));
    Tablecolumn colum = (TableColumn)(fxer.getAt( "#"+yd ));
    //assertNotNull( "Table View cannot be found", tableView);
    tableView.getSelectionModel().select(1, colum);
    Thread.sleep( 100 );
    FXApp.initializeIfStageExists();
    if (FXApp.isInitialized()) {
      fxer = FXer.getUserWith( FXApp.getScene().getRoot() );
    } else {
      throw new RuntimeException( "Could not find a JavaFX Stage" );
    }
    fxer.waitForFxEvents();
  }

I know my code has problems but I'm really not sure how to proceed. I already did lots of online research but unable to find a solution how should I proceed and which methods should I use. Output is:

error: incompatible types: Node cannot be converted to TableColumn

I know I cannot cast Node to TableColumn but I don't know how can I do to click on the child checkbox.

Also tried this code which clicks on the Parent checkbox:

public void clickChild(String id, String yd) throws Exception {
 fxer.clickOn(fxer.getAt( "#"+yd ));//id of table column
    TableView tableView = (TableView)(fxer.getAt("#"+id));//id of table view
    CheckBox cb = (CheckBox)(tableView.getSelectionModel().getSelectedItem());
    cb.setSelected(true);
    Thread.sleep( 100 );
    FXApp.initializeIfStageExists();
    if (FXApp.isInitialized()) {
      fxer = FXer.getUserWith( FXApp.getScene().getRoot() );
    } else {
      throw new RuntimeException( "Could not find a JavaFX Stage" );
    }
    fxer.waitForFxEvents();
  }