MacBook Pro - Software won't install onto my MacBook Pro's hard drive

Hi.

I'm trying to install Battery 3 which is some music production software, onto my hard drive but for some reason it won't let me. It keeps saying that I only have 4GB of free space on my hard drive when in fact I have over 220GB of free space. I have only had my MacBook Pro for a few months so I know there is at least 12GB free for Battery 3 to install...

Just wondering what I can do to solve this..?

I have been on the Native Instruments website who are the company behind Battery and they said to come on here for some advice as they can't seem to solve this issue.

Here's some info for you about my Mac which may or may not help:

OS: 10.5.7
PROCESSOR: 2.4 GHz Intel Core 2 Duo
RAM: 4GB 1067 MHz DDR3
DRIVE SIZE: 250GB and I currently have 222.71 GB left

Thanks for the help!

-Alex.