Zenworks 11.1a (updating to 11.2 soon)

Target machine: Win XP SP3

I've scripted a very basic printer install in Zenworks. In the end, I want the printer to be the default printer. I doesn't matter in which manner the script is defined, the following line doesn't run right:

c:\windows\system32\cscript prnmngr.vbs -t -p "printer name"

This line is supposed to set the named printer as the default. If I manually run the command on the workstation it executes correctly, but not from Zenworks running the scripts. Soon, we're going to install 80+ new printers across 10 sites to 1000 computers in a small school district.

Using "rundll32 printui" doesn't work through Zenworks either.

This problem is only for setting the printer as default; all other script parameters I'm using work fine. Any suggestions or fixes?