@Xenograg
I don't get why you're rolling to check for traps for the player behind the screen.
Why isn't she rolling?
If she was rolling she would know she rolled low and your answer of "no traps you can detect" would be sus.
She could then either not open it, or ask for a fellow PC with decent investigation to look at it with a higher DC.
That's kinda the point of dice, and why it's funny when people roll low. They still "think" they're fine but the player knows she may not be.