Link my WSS to Project Server 2003

I’ve encounter the problem like this:

i’ve installed Project server 2003 and WSS in the same
server.
and i’ve upgraded the WSS by the Project Server install
disc.
However when i tried to link the Project Server to the WSS,
It can create the "Public Documents site "
and all of my link can work properly.
However when i click "save changes" in Admin > Manage WSS,
it tells me that "the server is not extended with WSS"

whats wrong with that?