Screenshot uploaded to steam through steam api has different colors

Hi
so I got steam overlay to work, with the achievements and all that, but the problem is when I take a screenshot using this in a step event persistent object:

if (steam_is_screenshot_requested()) {
if(!directory_exists("Screenshots")) {
directory_create("Screenshots");
}
var pre = "Screenshots/" + string_digits(date_datetime_string(date_current_datetime()));
while (file_exists(pre + ".png")) pre += "+";
var out = pre + ".png";
screen_save(out)...

Screenshot uploaded to steam through steam api has different colors