Cannot change colour of PNG file

Hi all,

So im cutting out the white background of a QR code so im just left with the black in photoshop and saving it as a png so i have a tranparent background. Next i open the PNG in illustrator as i want to apply a specific color profile to the image that my pinter uses ( cannot apply this color profil in photoshop ). I use to be able to change the images file by selecting it it and clicking the appropriate color sweatch but not that is not working. No matter what option I use, recolor, paint brush ect. it wont change the image color?

Any help of this would be great.

Thanks