Suse 7.1 -> 7.3 update vs. upgrade

Folks, I tried to update my 7.1 to 7.3 via ftp and when I said update existing system, yast2 told me there was no installed system in the /boot partition. If I do a fresh install it works. I want to know if it is possible to update an existing 7.1 installation to 7.3 where package by package every module is updated as necessary to 7.3 level. Seems like I can only do an upgrade to 7.3 erasing my present setup. Am I missing something here? Thanks, Babu __________________________________________________ Do You Yahoo!? Find the one for you at Yahoo! Personals http://personals.yahoo.com