could you please confirm if you receive any sort of error while importing?
Please share a screenshot of your import settings for further assistance.
You might want to check for the destination location and make sure it has full read and write permissions.
It's usually necessary to clean up whats left behind after updating OSX.
Try trashing the prefs. Start by quitting Lightroom 3.
Launch Finder and click the Go menu whilst holding down the Option (alt) key. Then go to Library >> Preferences and clear everything relating to LR3 which usually means deleting the following files:
Then re-launch Lightroom.
What is the Go menu?