Problem with rundll32 printui.dll script

[jonnyknowsbest]

I use the following script to install a printer connection to a printer stored on a web server:

rundll32 printui.dll,PrintUIEntry /b "\\

http://10.1.1.92\Printer1"

/if /f %windir%\inf\ntprint.inf /x /n "Printer1" /r "

http://10.1.1.92/printers/Printer1/.printer"

/m "HP LaserJet 4050 Series PCL 6" /u

rundll32 printui.dll,PrintUIEntry /y /n "\\

http://10.1.1.92\Printer1"

rundll32 printui.dll,PrintUIEntry /Xs /n "\\

http://10.1.1.92\Printer1"

attributes +direct

The first 2 lines work fine to install the printer and set it as the default. The third line also works to set the "Print directly to the printer" flag, but gives me a "Operation could not be completed" error, does anybody know why this happens?