bandsaw problem

Many possible reasons

1. The blade may not be sharp.
2. You may not be using the proper blade, you want fewer teeth per inch. You may not be using a wide enough blade to help absorb and dissipate heat.
3. Feed rate may be too fast.
4. The blade may be heating up in the cut and expanding thus lowering the tension on the blade and causing a tracking problem.
5. Your fence/guide may not be set to account for the natural drift unique to that particular blade.
6. While your saw may have the clearances to cut that deep of a cut the saw in general may not be up to the task of cutting that much wood with favorable results.

Also, did you remove the bark? I find the bark ruins blades pretty fast. I use a draw knife to remove the bark. Did you have a sled? I stopped using a full sled, and now use a sheet of ply I find it give me nice support on both sides of the blade, avoids some other issues I was having. YMMV...