I recently was in the center of a U-19 mens game. Red was winning 1-0 at the point of the incident. A Red forward kicked the ball in to the box and then two blue defenders stepped in front of him sheilding him from the ball and gained possession. Red player then forces his way between the two Blue players and in the process gets tripped and goes down in the box. In my opinion it looked like an accident and red went down really easy in the box. Red team demain's a PK I yell load and clear "NO FOUL PLAY ON" then my Linesman puts his flag up at the same time. I wave him down. They continue to scream and shout never noticing my linesmans flag. Red goes on to win 3-0. After the match my linesman tells me it looked like a HARD tripping from behind but he was only 50% sure and he didn't have the angle either. Did I make the right call?