all devices disappear after migration

hi, we try to migrate ldms 9.0+sp4 core server to another server. but after migration all devices are disappear.

the old server is windows 2003 r2 32bit, the new server is windows 2008 r2 64bit

the old server and new server both use MS SQL 2005 standard with sp4

we finished restore db from bak file, restore all files from old server, no error, login to console, we found all devieces and we can remote control them. but next day we login to console, all devices are disappear.

on the client computer, we manually run inventory scan, this computer will re-appear in console.

anybody can help us to resolve this problem?

thanks a lot.