Is systemic insecticide right for scale infestation on house plants and if so what should I use?

I tried a systemic insecticide on my scale-infested ficus a few weeks ago, but so far no luck. The same insecticide worked wonders on our huge outdoor tree that was infested with whiteflies, but maybe it doesn't work on scale. The label says it does though - I think it's the Bayer brand from Home Depot.

Systemic generally is not the best idea for scale infestations. An application of a dormant oil is recommend either in the fall, or in the early spring before the tree begins to bud. A systemic is best for root feeding, and burrowing insects