Translation

Hello,

Storm is actually all i was looking for to do my management for invoicing, etc... now, there is one problem, my site is completely in dutch, but storm isn't translated with it.
I've created a nl.po file in the translations folder, but the changes don't seem to take affect, i already cleared my cache, but nothing changes.
Strange thing is some items do get tra,slated and soome don't.

Does anyone have any idea what i'm doing wrong here.

thanks.
Kristof