Achievement Collectable In Boston (problem Solved)

In the Providence station I see the plan of the line (on the wall) in black but I cannot activate it, I only need this element to complete the harvest. Is this normal or anomaly

 

I noticed that halfway up the stairs (when looking at the stairs from below them) there was a black rectangle on the wall. I walked past it and it showed as being unlocked with a popup, but the black rectangle didn't change visibly. May be a bug, but it may not be the element that you are missing.

 

It is not this element

 

Shine the flash light on it.

 

Hi,
thank you for the answers, indeed by passing the light the card is active, I had forgotten the card on the gateway of Canton junction ! It is complete now