What devices do you have?
I had problems importing to N900 using PC Suite.

What I did was, import all the contacts you need to transfer to the N900 into PC Suite and sync it to an Symbian device (in my case N97)

Then on the N900, choose Import in Contacts and use Retrieve Data
Turn on the Bluetooth on the N97, the N900 should now be able to find it and start pulling all the contacts & calendars & notes from the N97 into N900

PC Suite does suck and Ovi Suite isn't support yet.
Nokia should really get this fix. Perhaps delaying the N900 was a good idea to get the ground structures all implemented first before releasing the device that none of Nokia software can fully support it.