[Scribus] silly question: how to print opacity?

[Zhang Weiwu]

Hello. Opacity in my scribus 1.2 could not print correctly:

0) view on the screen, opacity looks okay.
1) printed with ps level 2, opacity is always 100% (no transparency)
2) gsview the ps level 3 output, opacity is always 100% (no transparency)
3) export as PDF (compatibility: Acroread 4) and view with acroread5: 
opacity is always 100% (no transparency)
4) export as PDF (compatibility: Acroread 5) and view with acroread5: 
opacity is okay
5) export as PDF (compatibility: Acroread 5) and print with acroread5 at 
ps level 2: opacity is always 100% (no transparency)

So currently I could not figure out how to print with transparency yet. 
I remember in 1.1.x serious there is an option for "enable opacity for 
PDF 1.4" which is removed from preferency in 1.2. So do I need to enable 
anything special to get transparency?

Thank you.

environment: KDE 3.3 FreeBSD 4.10 with postscript level 2 printer 
(laserjet 3015)