Attachment problem after Repository Migration

I migrated the repository from V7.6 to V9.1.1. But when I try to open a folder with an attachment I get an error: 'Could not read attachment'. When I compare the eAttachment tables the eSize of the V7.6 table is twice as large (see attachment - I hope it works here ;-) ) This is a huge issue - so how can I solve this? Thanks in advance...