how to use xval() funtion in pss simulation

Hi, I want to use the Xval() function in PSS simulation, because i sweep the input power (dbm). can anybody help to use that function...!

Describe your situation correctly.
You don't describe anything.

Just use like below function, it gives the x value of your graph.
xval(vh('pss"/net5"'(1)))

here net5 is input net.

You don't describe tool name which you use.
Show us followings.

(1) Correct simulator name
(2) Correct post processing tool name