Brown's side had the best of the game, but could not find the net, making it six games from the last nine in which they have recorded a blank.
Brown admitted: "It's the story of the season here. I can count six scoreless draws, and in all but one I think we were the better team. We know the problem, and if you know the problem, the remedy is there for you.
"As we're past the transfer deadline it might take until next season to remedy the situation. Someone else to score goals would put us in a really good position. We're missing chance upon chance, and it's really disappointing."
Brown feels his side are nevertheless performing well, and battled hard against a Motherwell side who lie second in the Clydesdale Bank Premier League.
"We can see the team are playing well enough and defending well. I think Motherwell are the second best team in the country, and we've played well against them - that's three draws against them here this season."
Brown's side face Celtic next week with their hopes of a top-six finish still in the balance, but the Dons boss feels they are still in with a shout.
"It's still very much alive," he continued. "You sometimes get points when you least expect them, as Ross County proved. I'm not saying we're going to beat Celtic, but we won't go to Celtic Park thinking we'll come away with nothing. While there's a mathematical chance, we'll still be fighting. We're playing well enough - if we could just buy a goal - to be in the top six."
Motherwell's Stuart McCall focused on the positives as his side maintained second place in the SPL and all but sealed their place in the top six ahead of the league split.
He said "I thought the first half was a really poor game. There wasn't much goalmouth incident until Darren Randolph's really good save just before half-time. We don't get many clean sheets so we're delighted with that one. We've taken four points from two tough away games, which we're pleased with."