Undesirable light appearing

Hi D5 team!

I am having a issue in my render. There is a light appearing on the ceiling, just like it has not been closed. I checked the model and even created another ceiling on the top of this one, but this light still comes through it.

How is it possible to fix It? I need to do larger scenes and I am worried about it. Can I really trust the render for greater jobs?
Thank you!

Hi,could you please send your project folder and with some screenshot to my email:2353817277@qq.com, we must do some test. thanks a lot!