Aberdeen manager Jimmy Calderwood was hugely disappointed to lose out in the CIS Insurance Cup semi final.
Calderwood was upset by the defensive errors he witnessed
"We worked so hard to get here but then you see the mistakes and the poor passing," he said after the 4-1 defeat to Dundee United at Tynecastle.
"We've let down the 7,000 fans that followed us down here.
"We used to be a tough outfit to beat when we went 1-0 ahead but that is not the case these days and we've got to get back to the drawing board."
Aberdeen went ahead through an Andrew Considine goal but almost immediately surrendered the lead and then fell apart in the second half.
"We got a break with the goal, took confidence and we were knocking it about for fun," Calderwood told BBC Sport.
"But we got done from two dead-ball situations, which they live off, and it was sloppy defending from us.
"The last two goals were down to misunderstandings between Zander Diamond and then Scott Severin and Jamie Langfield.
"And those sort of mistakes have been following us all season."
Aberdeen also had striker Lee Miller ordered off for picking up two bookings and Calderwood was not impressed.
"I thought the first yellow card was harsh but he should have never have put himself in the situation to get another one," he added.
"Lee was sent off for petulance and he should know better than that."