Is anyone good with Numbers? Basic question

So I'm trying to track expenses, but Numbers doesn't space the x-axis entries (the date) like it should. It treats each date as just the next entry instead of spreading it out further if the date is farther away. i.e. if the dates are 1/1/13, 1/10,13, and 5/30/13, they are all three spread out evenly instead of the 5/30/13 mark being further away. Excel does this properly, but I can't figure out how to do it in Numbers. Help? Here's another post if that wasn't clear:

http://forums.macrumors.com/showthread.php?t=1415774