I find if I've typed the serial number in notepad first, when you enter the serial number, check to make sure you aren't accidentally adding a space somewhere. Also remember there's a thing with O and 0. If I recall Poser serial numbers doesn't use O, but I could be confusing that and it might be the opposite.

The dust settled, thinking "what a fine home, at least for now" not realizing that doom would soon be coming in the form of a vacuum cleaner.