the new VT is in one of four rooms in B1&B2. But when you entered one of those,
you have to defeat an enemy VT, and after, you have to bo straighit into the room.Then you will find a new door. New VT is there(not all four rooms. One of them.)
If you find it, osccur 1 will call you. After that, you don't have to open other doors.
When you open the first door, hide left side of your VT behind the wall so that you won't get damage from enemy VT.