I have just started to get into some officiating at the junior level. I have had a few assignments, and I'm still hung up on overruling line calls. I'm in a position where I would rather make no call at all than make the wrong call, but I've been presented with some difficult situations. I'm still learning and picking up on things, but line calls are always controversial to say the least. More than anything else, I just want to do justice by the players and avoid conflict. The last event I did as a roving umpire had me standing at the net post for a boy's semifinal in a three set match-tiebreak format. I did not make an overrule until the match tiebreak, in which I ended up overruling two line calls on the same near sideline against the same player, who I did not suspect of foul play. His opponent hit two down-the-line point-ending shots that either landed on or very near to the sideline, and I ended up calling both in. At the time I felt that both shots had landed partially on the sideline, but after the match it occurred to me: how can I be sure? I could have very well gotten them both wrong, and it has nothing to do with incompetence. It's hard to call lines when you're standing on one side of the net post, and it's hard to be confident unless you're standing on the line in question. It would be like a chair umpire making calls without lines-people, except it's even harder because of the lower vantage point. I'd appreciate any constructive feedback. Thanks.