Inconsistency in the device partitions listed under "/proc/partitions" file and "fdisk -l" output

Issue

• can not read from a disk path
• can not read from a partitions created on multipath device (otherwise I can do it on all other veritas disks) :

root@calypso:[/root]# dd if=/dev/sdbcx3 of=/dev/null count=20 
dd: opening `/dev/sdbcx3': No such file or directory
root@calypso:[/root]# dd if=/dev/sdbyg3 of=/dev/null count=20 
dd: opening `/dev/sdbyg3': No such file or directory

• why do we have difference between fdisk and /proc/partitions output ? fdisk show both partitions but /proc/partitions file does not show both the partitions.
• why do not we have partition 3 for scsi disk inside /proc/partitions ?