Export module in Indesign fails to overprint black

Question

Hi Everyone. I have a big issue that need help with. I have indesign files for printing that are exported to pdf for imposition. When I open the pdf in acrobat the text that is set to overprint only knocks out, irrespective of the settings I choose in making them. Now, the example: I make a yellow box on a page and type word 'overprint' over it. Indesign by default prints black to overprint (checked the preferences). To make sure it does overprint I duplicate the box and text and set the text in attribute panel to overprint. The page is exported to pdf: both files show that the black is knocking out. Now for the hardware and software: I have CS5.5 with the latest update, using OS-X 10.6.8 Intel core duo 2.26GHz, DDR3 ram and plenty of space. No, I have not installed any new software and no third party plugins. I have recreated the preferences file but no difference. Tried also to export as eps but the same result. I also have a Windows 7 laptop with the same CS5.5 version and this problem is not happening on the laptop, only on the mac. The export engine in InDesign is not working as it should be (the pdf extension if v7.5.2.3) and having a lot of issues getting work ready for printing. Does anyone have any suggestions, ...and how do I get Adobe to take notice of this issue? Much appreciated and thanks in advance.

Answer 1

No reason I can think of that the PDF would have the Black at knockout.
You're definitely using the default Black swatch named [Black]?
Just tried there with your PDF settings, and it worked fine, the black overprinted no problem.
The only things I can think of is that the Black was not 100% tint.
or
It used a transparency from the effects - with isolate blending ticked
It's a total guess though, I'd have to see an example of the file.
If you can provide:
Example INDD file
Sample PDF
InDesign go to Adobe PDF Presets and Define... and SAVE the PDF preset and upload that too
That would be great.