Reply To: Question regarding Indesign Cs4

You might check you Export dialog settings. If you used preset for [Smallest file size] there is an image compression – under Compression section on the left side. If you need this for print, than you have to choose [Press quality] with image quality 300 ppi.

Another possible thing is, that your image is not linked. Check your Links panel and see if there are any warnings. If so, you have to link them in order to display them properly in PDF.