I purchased a Vietnam Airlines ticket using Delta SkyMiles (award ticket) but the app shows my seat as unassigned. I called Delta to get the VN PNR but whenever I try to lookup my booking on the Vietnam Airlines website or app, they say that the information is invalid. The rep confirmed the flight is ticketed with an 006 number, but I can't find any more information about it. Is this normal or should I call VN for this?