CS 6 - Cannot copy a group into another document

I used to copy a group of layers into another (opened) document. Now, that I installed Photoshop CS 6 (Windows 10), the same function doesn't work properly anymore. When I try to copy the same group as I used for years, the other document in photoshop cannot be found. I only can be copied it into a new document (but not an existing).
After searching for the "broken" layer, which causes this problem, I stumbled onto a "color lookup"-layer. When I delete this layer, I can copy the group into another document as I used to do before. If I leave this layer, or create new the same layer, it doesn't work. This seems to be a bug in photoshop with windows 10 (with windows 7 I didn't have this problem). How can I solve this?

The Error Message (in germany): "Der Vorgang konnte nicht ausgeführt werden, weil eine Einstellungs- oder Füllebene nicht in den Modus des Zieldokuments konvertiert werden kann".

(This means something like "...one layer cannot be converted into the mode of the new document...)
The color modes are the same though.