Free throw violation

[donjarrett]

During a Jr Hi rec game, encountered this situation. A1 shooting 2nd of two. A2 is occupying lane space at top by free throw line. Once shot released, A2 turns and heads back to her backcourt. I called a lane violation because of leaving her space before shot hit iron, basket disallowed. Coach (high school official & some college) says this wasn't a violation because she didn't break the vertical plane of the lane boundary. I stuck with my call and said I would check the rules book. Rule 9-1-9, pg 52. If I read this correctly, I think I'm right. If not, help me out.