I didn't ever have a form 3468 and it was still giving me an error and preventing me from filing. I entered the details on line 6 under "other" so it had something to total and it worked. (amounts not shown here)
Code AH to ZZ: Other Information
Other * (enter description):
Turbo tax forcing this: Box 20, code AJ
Aggregate Business Activity Gross Income or Gain
Aggregate Business Activity Deduction
We had NO gasification/coal activity, only solar cookers
