I would open the table CurrentTableName in VFP6. Then copy to NEwTAbleNAMe fox2x with cdx. Then make backup/move table CurrentTableName. Then rename NEwTAbleNAMe to CurrentTableName. After that it should be open in any FoxPro from 2.5 and up.
If you still get the message "Not a database file", it means, the file header is corrupted and must be fixed. As far as I know, here is a difference between VFP6 and previous versions: if the record number by Header is less then the actual number of records, VFP6 IGNORES it.

>Thans Yuri, the problem is that fp2.6 does not recognize the table. It >says: "Not a database file".
>Is there a way to make the table backward compatible with fp2.6?