Can't add scene to build setting

For some reason, the window in FileBuild SettingsScenes in Build is locked as in the attached screenshot and I am unable to add further scenes by dragging or the "Add open Scenes" button and I can’t find a reason anywhere…

please help me!

Look at the message on the bottom-right part of your screen.
You are using a version control and until you check out your changed assets you won’t be able to make changes to build settings.

@RahulRaman Hello, Im a newbie in unity and im making a simple game. I have the same problem , I attached a screenshots, idk what I need to do. I didnt find any answers, you are my only hope.