My if/else code doesn't work correctly.

Question

If I remove the Scanner function if works. However if I allow user to enter the input, it does not work correct. I can't spot what's wrong. Please help!
import java.util.Scanner;
public class Club{
public static void main( String args[] ) {
String lastName = " ";
Scanner sc=new Scanner(System.in);
//allow user to enter last name.
     System.out.println ("Please enter your last name.");
     sc.nextLine();
//user may join club is lastName is Lim or Tan.
if(lastName=="Lim"||lastName=="Tan") //This is the relational expression
{System.out.println( "You may join the LIM & TAN club as member.");
else
// user may not join club if lastName is not Lim or Tan
{System.out.println( "Sorry");
       System.out.println( "You may not join as member.");
return;
}

Answer 1

I change it to this way, but it still doesnt work...
import java.util.Scanner;
public class Club{
public static void main( String args[] ) {
String lastName = " ";
Scanner sc=new Scanner(System.in);
//allow user to enter last name.
System.out.println ("Please enter your last name.");
sc.nextLine();
//user may join club if lastName is Lim or Tan.
if("Lim".equals (lastName)||"Tan".equals (lastName)) //This is the relational expression
{System.out.println( "You may join the LIM & TAN club as member.");
else
// user may not join club if lastName is not Lim or Tan
{System.out.println( "Sorry");
System.out.println( "You may not join as member.");
return;
}