Object transparency fade issue

Hi all,

I want a object to fade in to the scene with the help of a keyed Mix node between a Transparent DSBF- and a Diffuse node.

When i set the Mix node to 100% Transparent i get some weird things going on in the scene. I already set (in Light Paths section) the transparency Max to like 1000ish but that doesn’t help. Can anyone tell me how to properly fade these objects in to the scene?

Disabling denoising did the trick!