I would go directly to the drain line on this unit. It sounds like it has no siphon break. Most dishwashers drain into the sink drain, using the sink itself as a siphon break. If the drain goes directly into a drain line without the benefit of a way to get a "breath", the water will siphon out, leaving no water in the unit to circulate. If the unit cannot be drained into the sink drain, you will most likely have to add an aftermarket siphon break to prevent the siphoning effect. I hope you find this helpful!