It took me a while to figure out how to get this to both vacuum and seal in one go. Turns out, the instructions aren't super clear. That said, here's what you need to know: There's an insert that goes in the vacuum area. Remove that to seal bags. Make sure that the open mouth end of your bag is in that open area to get it to vacuum. If it is wrapped around the notches, over the vacuum hose spot, or extends out the other side of the sealer, it will not vacuum seal. The bag needs to be between the notches on the sides of the sealer side and the open end must be in the area where the insert was. That was the only way I could get a reliable seal.