How are you printing it (including are you using a PostScript printer (driver)?
How does it look if you print ot or Save As PDF and open it in Acrobat/reader?
Does it also happen to other artwork?
What is the phase of the moon in your part of the world (over here it was full two days ago)?
Edit: And what Steve is going to say.
Check whether the white bits are set to Overprint (Attributes panel)
This shouldn’t be possible in an RGB file but you never know your luck when it comes to printing :-)
Thanks to both of you for your fast answer!
Finally I found the problem. It was just a problem of the printer. So I used another one, and problem solved!
Btw Jacob, considering your question about the phase of the moon I have no clue. In Germany the sky is covered by clouds since... I cannot remember when it was last time I saw the moon or the sun!
That is even more serious than your printing issue, Mirna (even before you solved it).
Mirna: Good job you found what the trouble was.
Jacob: A couple of days after full moon in any part of the world, but Illie’s moon phases have long ceased to work (dunno why).
Eyes and Shopping days till Christmas are still there though, if you know where to look for them :-)
You are right about everything, Steve. Someone should mend the moon, but then I should be more easily found out.