[Scribus] png-file with transparency is printed with black background

[Ekkard Gerlach]

Hi, 
I'm back again, thx to Christoph Sch?fer. He gave me some hints
in a PM. The problem with wrong colors is solved by printing via pdf. 

The problem with transparency with png's is still unsolved. Printing 
transparent png's (f.e. http://www.aiai.de/x.png) via pdf results
 in BLACK background: http://www.aiai.de/x.pdf.
The black background can be viewed with xpdf on the screen or 
as result when printing to Konica Magicolor 2350, Kyocera600, ..

Is it the fault of the png? - I generated it with gimp, new image, 
transparent, inserting some stuff, saving as png. 

Or is it the fault of inserting in scribus? Or the fault of scribus 
itself? 

thx
Ekkard