Data Importing Error in Migrated Ms CRM 2011

Dear Experts ;

I have a situation in Migrated (4.0 to 5.0) Microsoft CRM 2011 in which data importing associated

The issue is - I am successfully migrated Ms CRM 2011 from Ms CRM 4.0 through Deployment Manager. After importing, all entities are working fine. Then I import some data’s (csv file, 3 KB) into Lead Entity but they couldn't imported with no success messages or no failure messages

Please give me your ideas and suggestions on this:-

shown in the screenshots belowNo



 Thanks & Regards