[xubuntu-users] Encrypted disk install - Swap won't turn on

[Gordon Burgess-Parker]

Hi all,
Xubuntu 14.04 installed using the Disk Encryption and LVM options.
Swap is showing as unavailable in System Monitor, shows on the Disks app 
as /dev/xubuntu-vg/swap_1 contents unknown
Contents of /etc/fstab as follows:

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type> <options>       <dump>  <pass>
/dev/mapper/xubuntu--vg-root /               ext4 errors=remount-ro 
0       1
# /boot was on /dev/sda1 during installation
UUID=45f4cbb0-45ce-4337-9d5b-ac702adbd23f /boot           ext2 
defaults        0       2
/dev/mapper/cryptswap1 none swap sw 0 0

How do I turn Swap on? (This particular machine only has 2gB RAM.......)