Stirling Albion - who back in October had inflicted the Ibrox side's only Irn-Bru Third Division defeat of the campaign so far - stunned Rangers again as Ross Forysth's second-half header at Forthbank cancelled out Andy Little's 22nd goal of this term.
The Binos' leveller came as the Light Blues' back four failed to read a Kieran McAnespie free-kick, despite the former Hearts and St Johnstone man giving them three tasters of his dead-ball talents in the opening period.
The Glasgow giants also conceded from a cross into the box against Berwick on Saturday and came unstuck in their recent William Hill Scottish Cup defeat to Dundee United as the Tannadice side benefitted from a similar source.
McCoist insists his men have been well drilled on the art of defending set-pieces into the penalty area but doesn't belief a lack of guts is the reason behind their continued problems.
The Ibrox manager said: "Once again we defended a free-kick appallingly. It's a problem, because the opposition's best chance of scoring is from a set-play. I don't know the percentage, but I bet the percentage of goals that we have lost in the league from set-plays is really high.
"We are not attacking the ball well enough in that area and it's a problem. We have lost a goal here and we lost a goal on Saturday from a set-play. It's something we are aware of but we have to take responsibility as players to go and defend the goal. We haven't done that.
"It's not a lack of bravery. And I don't believe it's a lack of organisation, because we work on them long enough and hard enough, I can guarantee you that. It's maybe just an inability to do your job at the right time."
Binos boss Greig McDonald missed that famous October triumph because he was getting married on the same day. He was back in the dug-out for this latest visit of the Glasgow giants but insisted it is his players who should be getting the plaudits for putting up another shut-up job on their frustrated opponents.
He said: "It's not really about me. My wedding got a bit too much coverage the last time. That was more about the efforts of the players, which was a bit like the Alamo, as we had to defend for so long. The bizarre thing this time was that Rangers didn't cause us that many problems. David Crawford has had a couple of saves but so has Neil Alexander. It was a fair point."