Why might the mount command fail when specifying the device to be mounted by LABEL in RHEL?

Issue

The mount command in Red Hat Enterprise Linux supports the use of file system labels to identify the device to be mounted. This is an alternative to specifying the device path explicitly and is useful in situations where the device node may change (for example, SCSI disks presented from a storage area network or removable media). For instance, /home is mounted with "LABEL=/home"...