Printer configuration error

[jtouso]

Hi,
Knoppix 5.3.1 installed on hd.
Knoppix icon in toolbar...Configuration...Printer configuration...(kdesu '--' /usr/sbin/cupsconfig)...root password and...the problem:
Error! fail su conversation.
My password is ok but I can't use this way to install my printer. I use K icon/menu....Preferences...Printers and all ok
What happens with the knoppix-icon toolbar error?
Thanks
Jose