I worked with DB2 7.1 FixPak 3 on AIX 4.3.3 (ML 09) and I did an migrate action (from 32bit to 64bit) using the following command: (before that, I stop applications, stop db2 and everything.)
db2iupdt -w 64 db2inst1
but I got the following error:
SQL1707N Uable to migrate the instance word size.

Check the message from documents:
SQL1707N Unable to migrate the instance word size.
Explanation: There was an error while attempting to migrate the word size of the instance. Please contact your IBM service representative.
User Response: Contact your IBM service representative.

But now IBM Call Center is offline. Would anybody shed me some light? Thanks in advance.