Active sync 4.5 doesn't connect with J728

Hello,
I've installed Active sync 4.5 that came with my new 900C.
All works fine.
Except, now my J728 won't connect to my PC no more.
Is there a way to connect both devices?

Active Sync 3.8 is best for both devices.

S/F,
CEYA!

Thanks!,
Works fine now.