Hawk-Eye has apologised to the PCB in a letter after acknowledging an error made during Islamabad United’s three-wicket loss to Quetta Gladiators on Thursday, ESPNcricinfo understands.The incident occurred during the 11th over of the Gladiators’ innings. Off the final delivery of the over, Gladiators captain Rilee Rossouw moved across and attempted to sweep Salman Ali Agha but missed, with the ball hitting his front pad. Aleem Dar upheld an enthused appeal from the fielding side, and Gladiators promptly reviewed it.Hawk-Eye eventually determined not only that the ball had hit the left-hander outside the line of the stumps, but that it would also have gone on to miss off stump. When it was shown on the big screen, both the fielding side and umpire Dar looked visibly surprised, because the slow-motion replay appeared to show the ball straightening instead of gripping and turning. Static images of the impact on the pad also suggested a potential disparity between where the ball had hit Rossouw, and where the ball Hawk-Eye was tracking declared it to be hitting, with the former much more plausibly in line with the stumps.The letter addressed to the PCB Chief Operating Officer Salman Naseer and the Production Department, accepts that ball tracking for the delivery in question did not reflect the path of the actual delivery that had been sent up for review. It is not yet clear what caused the error.After the game, during an on-screen interview, Shadab Khan, the captain of Islamabad, made little attempt to conceal his frustrations.”I think technology made a mistake,” he said. “The ball-tracking showed a different delivery, and it was a match-changing moment. These sorts of things should be sorted out properly in such a big tournament. These mistakes should not happen. I bowled four overs here as a legspinner, and I don’t think the ball was spinning here. And they showed Agha [Salman]’s delivery hitting outside off stump and spinning away. I don’t buy that.”Compounding Shadab’s frustration was how delicately the match was poised. The Gladiators were building up a partnership after the loss of four early wickets, with Sherfane Rutherford and Rossouw rebuilding. The Gladiators were 82 for 4 with nine overs to go and needed a further 57 to win. What made them particularly vulnerable was a long tail, with United believing they could crack the game open with a breakthrough there.As things panned out, the duo put on a partnership that put the game out of United’s reach. They put together 62 for the 5th wicket, with Rossouw unbeaten on 34 right to the end.