CBR file are jpg compressed in a rar format
CBZ file are jpg compressed in a zip format
CB7 file are jpg compressed in a 7zip format
lot of files downloaded doesn't have the correct extension.
and with the bad extension, DO does not work well with the file
I've been concerned with this problem. That why I've made a fork of a previous DO script.
You can find it there : Comic Book CBx-To-CBx Convert & Resize v1.50 - #9 by oevesque
Just use the last checkbox.
If you don't want to install my program, try to rename your cbr file in cbz, and press F5 to refresh.