Preview Highlighting colours not showing in other PDF viewing programs

Hi,

I'm new to OSX and today discovered that Preview can mark up PDFs with highlighted colours - pretty cool

However when the saved PDF is viewed with other programs; Adobe Reader XI on both Windows and MAC and Foxit Reader, the highlighted colours are so faint you can easily miss them and its very hard to distingiush between yellow and green.

Anyone else come across this?

Thanks

Mike