i understand but when i go to Test Movie it says;

Symbol=Symbol 1, Layer=Layer 1, Frame=1: Line 4: '(' expected
}else if _root.last_button eq "third"){

Symbol=Symbol 1, Layer=Layer 1, Frame=1: Line 16: Unexpected 'and' encountered
and then on frame 10 (where he lands at the second button) have a check :