The error is that the room center is out side the room. The room center is calculated from all the verts, and is used to calculate things for ai, sound, and maybe more. So it might throw off the path of a homing weapon if the room center is not in the room. I have enclosed a screen-shot to show the room center. When you made the room a level, the player start is placed at room center by default, so in your one room test you have a player start outside the level.If you cannot see the room center, open a room and right-click on either the top, side or front view and check 'Show room center'.To fix this, I would recommend splitting the rooms up differently. Another solution would be to reshape the room so the room center is inside. This is not strictly necessary, even many of the original levels had this type of error, but for best game-play should be fixed.