return to play on previously created planet

[Delice1]

Hi. New to SPORE. I can create new life on a new planet, but when I try to return to this planet later (i.e. click on it, and press the blue "play" triangle) nothing happens. So I can only go to new planets and create new life each time I play the game, but can never return to games I previously created because the blue play triangle never works. Can someone help?