ice maker stopped producing ice

Refrigerator purchased with home. Water in door was a slow stream but it worked and the unit produced ice. Then one day the unit stopped producing ice. Replaced filter- no ice. Replace water inlet valve- no ice. Replaced ice maker inside freezer- no ice. Temp is 0 degrees. Unit is on. Tube is not frozen. Unit still does not produce ice! What mechanical or electrical component calls for the water valve to fill the ice tray? The ice tray is not filling with water. Any suggestions?