Hi Derek,
I have found where I was going wrong. On the selector options, I was selecting "Grouped Values", to see the above option I have to pick "Features".
But another error (bug?) what I have found is sometimes if we switch between the tab or windows some of the options gets disappear, refreshing the page doesn't work and I have to close the entire window to get everything back.
e.g.in the above case when I switched back from "Grouped Values" to the "Features", an option to label the selector has been disappeared and I have to close an entire window and reopen it.
Any Suggestions?
Thanks,
Anu