pngquant not running

[steve231293]

Hello there,
Could you help me this problem, please?

I installed lastest version (2.18.0) pngquant lib successfully.
It worked if i add this command to terminal. It regenerated a compressed image file.

pngquant sample-image.png

But it's not working with your library. I don't have any ideas about this problem.
Maybe we need some configs that make PHP with PNGquant to working together?

Thank you in advanced.