I just downloaded and synced clam wallet then imported bitcoin wallet.dat file. Then did the same for litecoin and dogecoin wallet.dat files.
Balance is still zero clams.
Is there any other step I have to do or simply those addresses were empty on May 2014 (can't remember for sure)?
There are no more steps.
Pick an address, and look at
https://blockchain.info/charts/balance?format=csv&address=ADDRESS to verify the balance on 12th May 2014.
Sorry for being a noob but it seems to me some addresses I used were not empty: may you please check if I'm correct?
here are just some of them:
17hGb6CfGqXp9FpCXtrcR2Y16dX3UmBVFk
1AFizN1hhGtfG2eAdxVXW8xGodcJhHHaCv
12wU1fGk3CAbhtQRvrB1Xeb11TeHCyCBFp