Samsung Washing Machine Not Draining

I have a Samsung front loading washing machine (model number WF206BNW/XAA). I received an error code of ND which means it will not drain. I removed the drain pump and checked for clogs. I did find a penny inside the drain pump influent line which I removed. The pump impeller and motor looked fine. The drain hose looks fine with no clogs or kinks. I reassembled everything and tried another cycle. Everything is fine until it gets to the rinse cycle and I get the ND error once again. I thought maybe the pump was bad so I hooked up a connection to an old power cord I had and plugged it in to a 120 V outlet to see if it would spin. It did spin so I know the drain pump motor is fine. The impeller is fine. I reinstalled the drain pump except instead of hooking up the electrical connection to the connection from the washing machine I left my homemade connection hooked to the drain pump. I ran a cycle and when I get the ND error I just manually plug the drain pump electrical connection into the outlet and drain the water out. It works fine. There must be something else preventing the signal from getting to the pump. Any clues?