importing contacts not found

importing contacts not found

Hi im using Zoho Premium, 

When importing contacts, i obviously select my file to be uploaded, what to do with any duplicate records,
I then map the Zoho CRM field names with the appropriate column names of the source file that you import. 

all is correctly selected 
and still after a conformation email that the import has been successful, there is still no contacts that appears/are available in the contact field.

please help?

Regards
Zia