Ok, I managed to solve my problem, the issue was:
1- CSV import/export needs to be done very carefully (especially using mac, just like my case)
2- Custom Fields, those with numeric values, and being of the type Drop Down, need to be imported exactly like they are in the CS, so if you have a value "01", and you import "1", it will not be recognized.
A VERY IMPORTANT NOTE: DO NOT AUTO-INSERT THE USER IDS while importing tblclients table, like what I did, and it forced to me to delete everything and do everything from the beginning. The reason: IDs are of the to be auto-increment in database, so if you inject it manually, the system will not consider those IDs as used, so as a result, adding new clients will fail, and your system will remain without the possibility of adding any new client.
Thanks,
Ali.