Why codeigniter shopping cart class doesn't allow any special character in the name?

I have a question just like in the title - Why codeigniter shopping cart class doesn't allow any special character in the name? When I'm adding some item with normal name containing only standard characters it works like charm. However if I add something like, say, "word / word" or something like that it won't add anything to the shopping cart. Can someone provide me with some hints on that one please?