Kindle App doesn't recognize new purchase - HELP!

I just got my iMac after year of drooling so I'm sorry if this is an easy fix and my brain, being subjected to years of PC use, just is too screwed up to find the "easy answer". 😉

I use the Kindle App on my iPad 2 and iPhone 3G (praying the iPhone5 release rumors are true for early next month!) and just installed it on my iMac. The problem is for some reason the app is not recognizing the computer being connected to the internet so isn't downloading the book I just purchased. When I go to "manage your kindle" on Amazon's website it shows the book as a pending delivery but when I open the kindle app all I see are the spinning arrows (syncing) and no new book. It also appears that the dictionary that is supposed to download with the app the first time a word is highlighted isn't getting downloaded.

I've confirmed that the app is registered to the correct account and that the firewall is disabled so I know that neither of these are issues. I have used the "check for problems" under the Help menu and it shows the network connection, hard drive free space and secure storage are all fine but the dictionary is not downloaded.

I am VERY frustrated and am at wits end so any help provided I would be immensely grateful for!