How to get this clean black-transparent effect?

[GraphicHero]

I would like to achieve the black-transparent effect that you can see in the picture below.

It doesn't work with lowering opacity (you get a dirty greyish kind of look that's far from clean, black and transparent) or 2 separate layers with different properties like color or overlay, same result there.



Thanks!

 

[Remote-Medic]

Created a rounded rectangle with the shapes tool, lowered layer opacity to 85% and vuola, looks fine to me:

 

[GraphicHero]

Ah... lol... that sucks... my vector background is yellow/white. That's what's causing the dirty grey effect.... it's not an image so I am not sure I can come even close to the desired effect... I'll play around a little more with it tomorrow and let you know what I've come up with.

 

[Remote-Medic]

ah okay, well just threw this together to try the colours and still doesn't look too bad to be honest. Just need to be careful on the opacity adjustment. My screens are calibrated if that makes any different.