At 0:42 of the second period in the Sabres/Stars game, Buffalo requested a Coach's Challenge to review whether Dallas was off-side prior to Jamie Benn's goal.
Review was not conclusive in determining whether Dallas was off-side prior to the goal. According to Rule 78.7, "If a review is not conclusive and/or there is any doubt whatsoever as to whether the call on the ice was correct, the On-Ice Official(s) will be instructed to confirm their original call."
Therefore the original call stands - good goal Dallas Stars.
Since the Coach's Challenge did not result in the original call being overturned, the Buffalo Sabres forfeit their time-out.