Then the database prefix is most likely all right, because there would be 0 records in the first table.
It's more likely, that the submit request is not arriving properly for some reason, so the values are not saved.
Can you please provide temporary ftp and administrator access to your site? I would like to do a line-to-line debugging on the affected plugin code.Best,
If you like my products, don't forget to rate them on codecanyon :)