iPhoto backup on TimeCapsule using encrypted disk image

Question

I have the following setup:

• Pics on my MBP
• Backups on my TimeCapsule
• iPhoto library alias pointing the real library on encrypted disk image

Every time I open iPhoto, it mounts the encrypted disk image. Once I close the iPhoto, it does the unmount.

Any ideas how I can get the iPhoto backups to work on TimeCapsule?