x32 to x64 convertion, Cyrus issue with annotations

[ABBAS Alain]

Hello 
we have got an issue trying to migrate a kolab from 32x to 64x , we had this issue already but though that was a process problem but now this is the third time that we have that. 

on the x32 bit system (tried with 2.2.2 2.2.4 2.3.4 ?)
we export annotation.db 
db_dump /kolab/var/imapd/annotations.db > annotations.db.txt

and on th x64 system we import the annotations (after all steps done)

by :
db_load -f annotations.db.txt annotations.db
chown kolab-r:kolab-r annotations.db
chmod 600 annotations.db

All seems ok but when you display the annotation with cyradm or IMAP command
the 4 firsts characters f the annotations are missing 
event.default becomes t.default.

Tried many time and all the time the 4 first charaters are missing , i had to make a script with cyradm to restore 
them the first time. 

Any ideas, somebody experienced that ?