When i try to update creative cloud i get the message that i have another creative cloud open and i have to close it first?

Once i had installed a trial from creative cloud. Now i bought the creative cloud. I want to use it but every time i open creative cloud i first have to update it. When i try to updrate i get an error that i have another creative cloud open on my computer and i first have to close that one. but i don't know how... I hope somebody here can help me! Thanks