New HD--error using Disk Utility for backup

I was attempting to backup my HD to a new External. I partitioned it using disk utility. However, when i went to create a new image of my internal to backup onto the partition i want it backed up on disk utility gave me an error, saying the "Resource Busy". Help Please! Thanks.

Why not just use time machine. Or carbon copy cloner ?

I used MACOS Extended Journaled

I Have OS X tiger. So i still don't have the ability to use time machine

checking out carbon copy cloner. thanks