Halifax notched only their third away win of the season at Victoria Road to ruin the Daggers' end of season party, as the home side unveiled John Still as their new manager.
Dagenham wasted no time in going on the offensive as Tony Perfect met Mark Janney's ball across the box and blasted a low drive straight at Mark Cartwright.
At the other end, Halifax were causing the Daggers defence their own problems as Colin Little flicked through to Lewis Killeen but his low effort was blocked by Tony Roberts.
Tarkan Mustafa then practised his long-range shooting with a 30-yard screamer blazed over the Halifax defence but was well held by Cartwright.
The game quietened down in the last 15 minutes of the half, but in the last minute Denny Ingram thought he had headed his side into the lead only for Janney to clear his effort off the line.
However, the gods were smiling on Halifax moments later when, deep in injury time, a push from Tim Cole on Little won the Shaymen the penalty.
A fine save from Roberts shut out Craig Midgley but the linesman wrongly believed the keeper had encroached off his line. Midgley was ordered to retake the spot-kick and this time he made no mistake.
The Daggers came out all guns blazing in the second half and there were a few hair-raising moments as Cartwright fumbled the ball in front of Chris Moore and then let the ball run under his foot for a corner.
The second half was played out mainly in the middle of the park and although the game ebbed and flowed from end-to-end occasionally, there was little to get excited about.
Precision in front of goal was poor by both teams. Alan Kimble's snap-shot narrowly missed the gym next door to Victoria Road and Danny Shipp blasted over the crossbar with ten minutes to go.
So Halifax clung onto their lead to take the three points but they can thank the Daggers poor finishing for gifting them the spoils.