Why am I losing quality when exporting to PDF from Numbers?

Hi guys, so I need to export a fairly large table I have to PDF so that I can get it into the report. It looks beautiful in Numbers, and then when I go to print, size it the way I want it, save as PDF, I get a crappy looking table....Lines have just randomly disappeared or faded. What is going on and how do I fix this?! It looks great in Numbers, I don't understand why it should look any different when I print to PDF.... Here is a screen shot inside Numbers, notice the lines look perfect....then a screen shot after exporting in Preview, notice how some of the lines are totally gone. You'll see the rows for "depth" have a dotted line to dived them....in preview the dotted line just disappears in one spot, but not in another. It's totally random and I've no idea how to fix it....