if statement issues

Hey, im having some issues with my if statements. Im using linked lists to keep details on students and ive made a interface class to make the program more user friendly. When the user types 1, it will bring up the add student interface, 2 is delete student interface and 3 should be print the list, but for some reason, when you press 3, nothing happens. I dont believe that i have errors in my code because if you type a println statement in the box and then press 3, Nothing happens. Here is my code -

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package lab8;

/**
 *
 * @author Aled
 */
import java.util.Scanner;
public class RegistryInterface
{
    Scanner sc = new Scanner(System.in);
    Registry reg = new Registry();
    public RegistryInterface(Registry theRegistry)
    {
    }
    public void doMenu()
    {
        Boolean quit = false;
        while (!quit)
        {
            System.out.println("Registry Main Menu");
            System.out.println("******************\n");
            System.out.println("1. Add a Student");
            System.out.println("2. Delete a Student");
            System.out.println("3. Print Registry");
            System.out.println("4. Quit");
            System.out.print("Select option [1, 2, 3, 4] :> ");
            int userInput = sc.nextInt();
            if (userInput == 1)
            {
                doAddStudent();
            }
            if (userInput == 2)
            {
                deleteStudent();
            }
            if (userInput == 3)
            {
                printRegistry();
            }
            if (userInput == 4)
            {
                quit = true;
            }
        }
    }
    public void doAddStudent()
    {
        boolean addAnother = true;
        while (addAnother == true)
        {
            System.out.println("Add student Interface");
            System.out.print("Enter forename\t :>");
            String forename = sc.next();
            System.out.print("Enter surname\t :>");
            String surname = sc.next();
            System.out.print("Enter student Id\t :>");
            int studentId = sc.nextInt();
            Student student = new Student(forename, surname,studentId);
            System.out.println(student);
            reg.addStudent(student);
            System.out.print("Add another (Y/N)\t :>");
            String add = sc.next();
            if ("n".equals(add))
            {
                addAnother = false;
               
            }
        }
    }
    public void printRegistry()
    {
        System.out.println("Printing...");
        reg.printList();
    }
   
    public void deleteStudent()
    {
        System.out.println("Enter a Student Id\t :>");
        int studentId = sc.nextInt();
        reg.deleteStudent(studentId);
    }
}

Thanks. Any help out there?