Photoshop :: Duplicate Groups Not Working In CS6?

Everytime I try to duplicate groups in photoshop cs6 to another open PSD file it usually works, but lately whenever I try to do it it only gives my the option to duplicate the groups to either a brand new file (an untitled file) or to the original file (that i'm duplicating the groups from). It won't allow me to duplicate them to another open PSD file.
 
For example, (in case i'm not being clear), say I have 2 files open such as A.psd and B.psd but i want to duplicate a bunch of groups i created in A.psd to B.psd. When i click on the groups i want to duplicate and the option box opens- in the destination box it only gives me the option of duplicating the groups to either A.psd (which is useless) or to a new file. It doesn't give the option to duplicate the groups to B.psd. It only gives the option if it's just a layer. I either have to merge groups into one layer or make them into a smart object and use the duplicate layer option instead. It's become a annoying problem because I want my groups to just duplicate. I shouldn't have to merge them in order to send them into another file. It has always worked until now.