I smoked 3 racks of baby backs on Sat. 3-2-1 method, using my 44" MB propane smoker. I was having trouble not getting any smoke at low temps so this time I used a smoke tube and that solved my problem of no smoke. The problem is the 12" smoke tube full only lasted for 2 hrs. Did I do something wrong? Others are saying they are getting 5 or 6 hrs.