directional lighting problems and doubts

Hello everyone i'm new in unity and i have a doubt about light. well i see in my scene a spot light at the end! and then why is it lighting if it has a roof ? the normal's roof is correct and i don't understand why happened this! why the light pass throught the object! am i the only that happen this? i'm new in Unity please help me because it's gonna me crazy.

Thanks so much for your help, and greetings from Machu Picchu - Peru