I also had trouble setting up multiple collections on my second account. Found these posts on page 100 of the "To Do" List Thread.
jayoneill: "The same thing happened to me. I was able to correct it by removing '?CollectionId=1' from the URL on the collection page.
As soon as I did that, the green create collection button reappeared.
I hope this helps."
vrooomed: "Thanks to Jay - I found a workaround.
If you haven't already set up multiple collections, the Collection Link looks just like it did before, no option to add a new collection. If you remove the "1" or "=1"at the end of the URL a big green button will display at the bottom of the collection page. Add a collection, and then you will always be greeted with the table that shows the differnt collections as well as the button to add new ones. (I had to play around in my son's account to see that.)"