I CAN'T CREATE A NEW SET

I can't create a NEW set. I have had this problem before and Musescore corrected it. It worked well for a time but has now recurred. When I go to my sets, they are all listed. When it is working, below the last set appears CREATE A SET. My last set is SONGS and there is nothing below. There is no help in Musescore.com HELP or in the HANDBOOK.
Be very grateful if you could fix it for me
Merle