Vision Duplicate Record Error

I'm recently worked out integration of Visual occupying AcuODBC to access cobol data, try insert same record into same vision table with modification to certain field values.  

Then it ended up to pop-up Error message as "ERROR [S0000] [AcuCorp, Inc.][AcuODBC Driver][ISAM]Vision duplicate record", but My data is about  successive to insert in.

Can anyone tell me why it happened and how to fix this? Thanks in advanced.