The first thing to do is check where you've told LR to copy things, the destination, specified at the right of the Import panel. Make sure this points to where you intend to copy your images to from the card.
What operating system name and version are you running on your Mac? The most recently available one is Mavericks 10.9.3. There was an issue with it, initially, where it hid the Users folder, and there was an update to iTunes shortly after, that fix this problem. If you are running 10.9.3 and are current on all your updates, then this issue would have been fixed and is not the cause of your LR copy failing.
Here is an article that goes over some things on Mavericks, where the Command-R section on "The big four: R, S, C, A" explains how to repair permissions.
http://blogs.computerworld.com/mac-os-x/23025/how-improve-mac-performance-os-x-mavericks-e dition
Here is another article about reparing disk permissions:
https://www.ifixit.com/Guide/Repairing+Mac+OS+X+Disk+Permissions/9314
You might also just tell us what your destination specifications are in the Import panel, in case we see something that seems off with them.