Whats up with that?!?!?!?!

So I went on the library website today to renew some books I have checked out and one of them would not allow me to renew the checkout because its on hold for someone else. Please explain to me how this is fair when I had a previous book on hold and when I checked the library catalog, it said the book was on shelf. I then placed it on hold and went down to the library to get it. I couldn't find it. I asked and they looked it up to discover that someone had checked it out just minutes before. So how is it fair that it wont let me renew because someone else has it on hold but the library can let someone else check out a book from the actual library when I have it on hold? There is no way I will pay a late fine for having the book back "late" when the library totally screwed me over. I don't think so.