在PHP中添加PNG图像后保存图像背景

I'm trying to insert a PNG image with transparent background in another image with a grey background, but when I use imagecopymerge, I got black background, and with imagecopy, I got transparent places in the final image line in the picture above :

enter image description here

 imagecopymerge($image, $turquoise, 120, 120, 0, 0, 16, 16,100);
 imagecopy($image, $turquoise, 140, 140, 0, 0, 16, 16);

Even if I used or not :

 imagesavealpha($image, true);
 imagealphablending($image, true);