"Not enough room" on OS X disk image

[KnoxIan]

I'm trying to store a FM8 file on a Mac OS X disk image (.dmg file). When I open the file from the mounted disk image and try to edit/add data, I get the error:

"There is not enough room on the disk to complete this operation. Make more room on the disk, then try again."

There's plenty of room (ten megs for a 68K file). It makes no difference whether the disk image is encrypted or not. I get the same message in FileMaker Developer (FM7) and FileMaker Advanced (FM8). Anybody else run into this problem?

[Ender]

Is it a read/write disk image?