I don't own a skimmer yet, but I do know that some of them have like a breaking period before they start working properly, so maybe you did hook up it right.
By the way, Do you have two different species of clownfish in your tank? and Do you have a bicolor dottyback in it too? I have one of those. I also can see a yellow tang and the blue fish, is it a damsel?. You have some beautiful fish there.