Not able to delete an icloud backup
I first had an iPhone 4. Since two days I have an iPhone 4S. Now i wanted to delete the backup of my iPhone 4. But I got a message, that I nearly reached my limit of 5 GB. So I selecedt the old backup and pressed delete. Then I got a message, that deleting is not possible. I cannot delete any of my iPhone-backups, but the backup of my iPad. I tryed it many times.
iPhone 4S, iOS 5