Issues while adding static routes to esxi 5.5c

hello,

I read this KB on adding static routes:http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2001426

But I am unable to add static routes to my esxi 5.5. host. am i missing anything here?

~ # esxcfg-route -l

VMkernel Routes:

Network          Netmask          Gateway          Interface

10.238.187.0     255.255.255.0    Local Subnet     vmk0

10.238.188.0     255.255.255.0    Local Subnet     vmk1

default          0.0.0.0          10.238.187.1     vmk0

~ # esxcli network ip route ipv4 add --gateway 10.238.188.1 --network 10.238.188.0/24

Duplicate route to network 10.238.188.0/24 found.  Please delete the old route first.

Kindly help.