Can't mount cd9660 file system.

[David]

Hi, everyone. I'm using freeBSD 5.1

I am having trouble mounting a cd9660 file system. I've
done this hundredths of times with no problems. But
for the first time, I am burning the iso image to dvd
medium. A dvd+r  exactly...

First, I created the image with the mkisofs command:

mkisofs -J -R -o backup.iso /win

The file size is 2.4G. 

Then, I use the burncd command:

burncd -f /dev/acd0 -s 2 dvdrw backup.iso fixate

No error messages...

Next,  I typed mount -t cd9660 /dev/acd0 /iso and gotten this  message:
cd9660: Invalid argument

then I type mount_cd9960 /dev/acd0 /iso and 
mount /cdrom, but got the same mesaage as above.

If you have any comments, I syrely appreciate it.
Thanks