It was a similar story to previous games, a good performance but lapses in concentration costing United dear.
United started on the front foot and an early Scott Thomson drive was blocked by Owen Stott with Sandy Carey unable to convert the follow up.
Another chance soon followed when Thomson narrowly missed the far post.
Rossvale had their first chance on the 10-minute mark, a cross from the left and Alexander headed wide with the goal at this mercy.
United opened the scoring after 14 minutes when Thomson took a pass from Ryan Murney to turn and fire home off the inside of the post.
United’s lead was short-lived though; when they were unable to clear ball on the left and from the resulting cross the ball broke to Kyle Prior who placed the ball past Darren Hill in the United goal.
United regained the lead in the 24th minute when Tom Neil won the ball in midfield and released Thomson who took one touch and from an acute angle fired an unstoppable shot past Stott.
As half-time approached Vale had a chance to draw level but a header from Peter Bradley stuck the outside of the post.
The second half started with the home team on the offensive but Bradley’s effort was high and wide.
United then had two great opportunities to increase their lead.
McElduff played in Thomson whose well struck shot was deflected for a corner by Stott. The resulting kick was met at the back post by Boyle but this effort came off the top of the crossbar.
This miss proved costly as United lost possession in midfield and Lee Roulston hammered home an unstoppable shot from 30 yards.
Worse was to follow in the 78th minute when Colin McMenamin pulled down Paul Brennan in the box.
McMenamin was shown a straight red card and substitute Damon Welsh made no mistake from the spot.
United had a late chance to level but Davidson's cross was missed by the inrushing Thomson.