Can't create sparsebundle

Hi,

I'm getting the following error message and consequently can't run backups right now: "The backup disk image "/Volumes/ReadNAS/gjbl MacBook Pro.sparsebundle" could not be created (error 28)". Does anyone know what error 28 means?

Here's the background: Timemachine was working fine. But my wife got a new Imac. To make space for the new imac on my Duo, i deleted the old sparsebundle files. I was able to set up the new Imac fine. The new Imac sparsebundle is there - I can see it when I log onto afp://XXX.XXX.X.XX, username = ReadyNAS - and I can run backups for the Imac no problem.

However, I can't create a new sparsebundle for my Macbook Pro.

I have a ReadyNAS duo, with 2 mirrored 1TB HDs, and am running the latest firmware. On Frontview, it says I am at 68% capacity of 925 GB used. The Imac has a 1TB HD, 440 GB on disk. My Macbook Pro has a 250 GB HD, 150 GB on disk.

Any help would be greatly appreciated! Thanks!