Why is total/used/free swap showing zero when "free" command is executed?

Issue

• Swap space appears to be zero

[root@test1]# free -m
             total       used       free     shared    buffers     cached
Mem:          2010       1918         91          0        217       1180
-/+ buffers/cache:        520       1489
Swap:            0          0          0

• Entry of swap in /etc/fstab

LABEL=SWAP-sda2         swap                    swap    defaults        0 0

• swapon -a throws the following error

[root@test1]# swapon -a
swapon: cannot find the device for LABEL=SWAP-sda2