Stockport 0-1 Dartford
Charlie Sheringham's strike earned Dartford three points at Stockport and deepened County's relegation worries.
Sheringham should have put the visitors ahead in the first half when he got onto the end of a James Rogers cross, only to somehow miss from two yards.
But the forward redeemed himself when he nodded home Ryan Hayes's delivery.
Matty Mainwaring came closest for the hosts with a shot that struck the bar, but they could not level, meaning they are now two points off safety.