Making it so ball heading reverses when it hits another sprite

I am somewhat new to App Inventor, and i am having some issues with an app I'm working on. My app is a copy of the game pong. im asking for a prompt response as this is a project that is due in early january.

OVERVIEW

My app consits of a ball that bounces off of a line and hits another wall to score. i am having an issue with the heading of the ball in that the ball is hitting the line but reversing direction sometimes.

ISSUES

getting the ball heading to not reverse when hitting the line

i have attached my latest version of the project

Ping.aia

Here's a link to a doc on my experiments with

balls bouncing off lines, with sample code ...

https://docs.google.com/document/d/1g71sI_rR7PqHGB83tAYZfNi7HvzIkWZ-xsvhFUxpplo/edit?usp=sharing

It has references to sites with angle calculations.