It works for me. What do you mean by "haven't had any luck"? Also tell us how are you going about to achieving this.
My method to do this is as follows:
1) Create a blank canvas of size 800px by 800px in PSE11 Editor (this depends on the size of your pictures, of course)
2) Now change over to Organizer by clicking on: Organizer Icon as shown in this picture:
3) Click once on your picture and copy it by doing CTRL + C in Windows or Edit >> Copy from Menu bar
4) Go back to the Editor window using the same method as 2 and paste the picture by doing CTRL + V or Edit >> Paste
5) Repeat the process for the other picture
6) Now move the pictures to the desired location using the "Move Tool"
7) Save your final picture.
You are done.