I tried Firebug, but there is just no error coming up. (please find an image attached, it may help)
i also tried to reinstall the payment module, and tried to install other payment options as well hoping that one of them will work. but all have the same error.
it looks that the js never return any data, just running in an infinite loop.

(the shipping cost pane is working perfectly...)

V: Ubercart 1.0 RC 2, Drupal 5.7

Any help would be appreciated.
Thank you!