and all entities have to be working right for the whole thing to draw.
First, the fireplace log is a gimmik in my opinion, spend a whopping $50 and have the chimney properly swept. that fireplace log cost $18.
Second, get a flashlight and stick your head up in the firebox and make sure that the door is properly shut.
Third, their may be an obstruction in the flue from a chimney sweep nest to a squirrel nest, the sweep will find that out for you.
Fourth, I forget the exact formula, but the top of the chimney must protrude over the highest ridge of the house that its built on. Another words the wind must sweep over the chimney and push the air and smoke away from that area and this action causes the draw. The fireplace chimney top must be higher than the house roof top.
Fifth, maybe you have a tree or shrubry blocking the wind.
here is another test for you. open the fireplace doors, light a candle in front of the doors, then blow it out, the smoke should go directly into the firebox and exit out.