Error Column Constraint

package lifetimemanagementcontrol;

import com.sun.scenario.effect.impl.Renderer;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.Menu;
import javafx.scene.control.MenuBar;
import javafx.scene.control.MenuItem;
import javafx.scene.control.TextField;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.ColumnConstraints;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.RowConstraints;
import javafx.scene.paint.Paint;
import javafx.scene.text.Text;
import javafx.stage.Stage;

/**
 *
 * @author Angelo Rocha
 */
public class MainScreen extends Application {

    Stage mainScr;

    public void start(Stage primaryStage) throws Exception {

        //Main Screen Default Definition
        mainScr = new Stage();
        mainScr.setTitle("Life Time Management Control");
        BorderPane root = new BorderPane();
        
        
        GridPane main_grid = new GridPane();
        Scene scene = new Scene(root, 500, 500);
        
        mainScr.setScene(scene);
        main_grid.setGridLinesVisible(true);
        main_grid.setVgap(10);
        main_grid.setHgap(10);
        main_grid.setAlignment(Pos.CENTER);
        
        

        
        
      
       
        MenuBar menu_bar = new MenuBar();
        Menu menu = new Menu("Expenses");
        MenuItem add_Expense = new MenuItem("New Expense");
        MenuItem edit_Expense = new MenuItem("Edit Expense");
        menu.getItems().add(add_Expense);
        menu_bar.getMenus().add(menu);
        
        add_Expense.setOnAction((event) -> {
            System.out.println("Olá");
        });
        
        root.setTop(menu_bar);
        root.setCenter(main_grid);
        
        mainScr.setResizable(false);

//        // Active  Expenses Components
        TextField expense_Total_lbl_txt = new TextField("dksksadk");
        expense_Total_lbl_txt.setPrefWidth(10);
        expense_Total_lbl_txt.setEditable(false);
        Text ScreenDescr = new Text("Active Expenses");
        HBox hbox_Gen_data = new HBox(10);
        hbox_Gen_data.setAlignment(Pos.CENTER);
        hbox_Gen_data.getChildren().add(ScreenDescr);
        Label expense_Total_lbl = new Label("Expense Active Amount: ");
        GridPane Active_EX_grid = new GridPane();

        Active_EX_grid.setAlignment(Pos.TOP_LEFT);
        Active_EX_grid.setPadding(new Insets(10, 10, 10, 10));
        Active_EX_grid.setVgap(20);
        Active_EX_grid.setHgap(10);
//        Active_EX_grid.setGridLinesVisible(true);

        Active_EX_grid.add(hbox_Gen_data, 0, 0, 3, 1);
        Active_EX_grid.add(expense_Total_lbl, 0, 1);
        Active_EX_grid.add(expense_Total_lbl_txt, 1, 1);
        expense_Total_lbl_txt.setEditable(false);
//        
//        // Paid Expenses Current  Year Components
        GridPane paid_current_year_grid = new GridPane();
        paid_current_year_grid.setPadding(new Insets(10, 10, 10, 10));
        paid_current_year_grid.setAlignment(Pos.TOP_LEFT);
        paid_current_year_grid.setVgap(20);
        paid_current_year_grid.setHgap(10);
//        paid_current_year_grid.setGridLinesVisible(true);
        
        Text Total_Paid_Expense = new Text("Year Expense");
        Label total_paid_expense_lbl = new Label("Expense Paid Amount: ");
        TextField total_paid_expense_txt = new TextField();
        total_paid_expense_txt.setPrefWidth(10);

        paid_current_year_grid.add(Total_Paid_Expense, 0, 0, 3, 1);
        paid_current_year_grid.add(total_paid_expense_lbl, 0, 1);
        paid_current_year_grid.add(total_paid_expense_txt, 1, 1);

        //Last Expense Added Cointainer
        GridPane last_ex_added_grid = new GridPane();
        
        Text last_ex_added = new Text("Last Expenses Added");
        Label[] last_ex_list = new Label[10];
        int i = 0 ;
                
        for (i = 0; i<10; i++ ){
        last_ex_list[i] = new Label();
        last_ex_list[i].setText("Valor de I:" + i);
        int o = 1;
        o = o+i;
        last_ex_added_grid.add(last_ex_list[i], 0, o);
        }
        
        last_ex_added_grid.add( last_ex_added, 0, 0);
        
        
        
        //Adicionando Containers ná grade principal
       
        ColumnConstraints cc = new ColumnConstraints();
        double a = 450;
        cc.setPrefWidth(a);
        cc.getPrefWidth();
        cc.prefWidthProperty().setValue(300);
        main_grid.getColumnConstraints().add(3, cc);
        
        main_grid.addColumn(3, last_ex_added_grid);
        
        
        
        mainScr.show();

    }

    public static void main(String[] args) {
        launch(args);
    }
}