"client-error-not-possible" error printing

[Bawenang]

Hi, I have a weird situation. I tried my application that uses CUPS library to print both in KDE and TWM. In KDE, it worked fine. But when I tried it in TWM, it asked for the user's password everytime cups needed to print. When I called the application from root, it didn't ask for password, but it returned a "client-error-not-possible" error. Anybody have an idea why this is happening? Does it has anything to do with the X system? Thanks in advance.