up - down arrow - mac Follow

i tired to google and search on the forums, but didnt find anything about this:

Am having problems with my Keys, when i start writing like this <di
the suggestion windows pops up, but m arrows dont work, basicly i cant choose <div> tag with keys, only with mouse.

i am on a mac osx lion... i get it to work on windows but not on mac... anyone with tips/tricks?
pissing me off that i always have to use the mouse..
thanks in advance.