Go back to Partition Magic and delete that dev3. Then go to www.google.com/linux
and run a search on dev3. You will see that's probably what's confusing SuSE installation. There is no filesystem type dev3. There are device designations, revision levels, but no filesystem called dev3.
Leave the disk blank, then try to install SuSE. Tell SuSE to use the free space on the third disk and let SuSE create and format the partition (filesystem type ext3, ext3, reiserFS, JFS, XFS, or some other valid fileystem type for Linux).
The red text is a warning: if you proceed you will do great damage to installed systems.