can not disconnect the pppoe with wrt54g

Hi all
My Linksys WRT54G's version is 2.2, firmware is the latest
version(download from linksys webpage)
It can work well.
I set the connect type to "connect on demand", but when I clicked the
"disconnect" button on "status" page, it will automatically connect
after 3 or 5 minutes.
I just want it disconnected forever after I click the "disconnect"
button, then "connect" manually.
How to handle this?
Thanks a lot