IIRC that one is a good diacetyl producer. You need to pitch a lot of it a little below fermentation temp, manage the temps during fermentation, and do a diacetyl rest or a long lagering time. The yeast will reasorb the diacetyl when they are done fermenting given time. With a starter you have not given them time to reabsorb. I also recommend yeast nutrient in the end of the boil.