Very simple.
The line
this.placeBlockLine(aint, aint2, (byte)HeroCraftMain.twoRiversLog.blockID);
Is casting the blockID to a byte. Remove the cast and it'll work fine. The problem you are seeing is that that the blockID is greater than the maximum value of byte, and the value is being truncated.
EDIT: I recommend turning on warnings on unnecessary casts to help prevent similar issues in the future. This can be done through the Eclipse settings for warnings and errors.