No appeal by fielders

A batsman was given out in a Bangladesh Premier League game between the Barisal Bulls and Rajshahi Kings sides in Mirpur on Sunday, however, there is no evidence that anyone appealed before umpire Khalid Mahmoud from Pakistan raised his finger. His countryman Umar Akmal came to the crease for Rajshahi to face opening bowler Al Amin Hossain, who sent down a straight delivery that the batsman tried to defend but failed and the ball hit his pads.
Al Amin was going back to his bowling mark and suddenly realised that the umpire had raised his finger. No fielders, including wicket-keeper Mushfiq, had bothered to appeal, but the umpire kept his arm up and batsman had to go.
It was more painful for Rajshahi soon after though as television replays showed the ball was not only missing leg-stump but that height was also an issue.

Law 31.1 states that "Umpire not to give batsman out without an appeal
Neither umpire shall give a batsman out, even though he may be out under the Laws, unless appealed to by a fielder. This shall not debar a batsman who is out under any of the Laws from leaving his wicket without an appeal having been made. "

Also relevant is Law 31.7 which states that "Batsman leaving his wicket under a misapprehension
An umpire shall intervene if satisfied that a batsman, not having been given out, has left his wicket under a misapprehension that he is out. The umpire intervening shall call and signal Dead ball to prevent any further action by the fielding side and shall recall the batsman.

A batsman may be recalled at any time up to the instant when the ball comes into play for the next delivery, unless it is the final wicket of the innings, in which case it should be up to the instant when the umpires leave the field. This applies even if the batsman has left the field of play and is inside the pavilion

In the situation described, the other umpire should have intervened and called and signalled "Dead ball", consulted with his colleague and recalled the batsman

Read more about Law 31 (Appeals) at the MCC website