content-aware scale greyed out

Hi, 

i have a file with two layers, a black background layer, and a pasted image on the layer above. I want to scale the image with "content-aware scale" but the option is greyed out. What am i doing wrong? It's not the first time i'm using the content-aware scale, but now it's not working anymore.

And yes, i made a selection, and yes, it's not a smart object or something. RGB 8bit document settings.