The Attacking For AI

So the main problem I have been facing has been making the enemy attack the player at a certain distance. And everything that I have been trying seemed to confuse me more. Mainly because no matter what it was that I did the AI would never respond well with the code or the behavior tree. Telling me that it couldn't find the task because it was never finding the task to be true therefore never actually doing the task. So I kept looking online and seeing if I missed anything or if there was anything that could help me understand why it wasn't doing the task. But then I saw that well more like heard in a video was something called a service. and it turns out that the service is what actually conducts the check to see if the AI is close to the player. So that was put inside of the game now but the only problem that it seems I have with the service is just understood the video that teaches me how to make it attack by breaking down a blueprint into code. In the end, though I do have everything I need inside of the game to make this task work hopefully around the end of this week with the help of my teammates if need be.