Why won't my GnuCash files open on (2011) MacBook Air?

Hi,

Grateful for any assistance that resolves this issue.

I use GnuCash (2.4.10) on my 2010 iMac (Lion). I keep my gnucash files on a USB stick and want to work with them on my (2011) MacBook Air (Lion). However, if I open the application and try to 'open' my file, I can't. For all intents and purposes, I have the same iOS and the same version of the app and can't understand why I can't use the files created on the iMac on the MBA.

If I launch 'Finder' and select the file I want to open, GnuCash launches just fine but I'm left staring at a blank screen with "Unsaved Book" in the Title Bar. I've tried several ways of opening the file with no joy whatsoever.

Do I need to install something additional to get this app to work on a MacBook Air? I am pretty IT-literate and can't for the life of me figure out what I need to do. I don't particularly want to have to compile the app from the source code...

Thanks in anticipation.