xpathdocument()

Hi All,

 I am trying to fetch data details from an XML file which contains XML code of an Process Model.
When I try to fetch the name , UUID or Pv's data using the following syntax 

for PV's : xpathdocument( docId , "processModelHaul/process_model_port/pm/pvs/pv[1]/name" )

for UUID : xpathdocument( docId , "processModelHaul/process_model_port/pm/meta/uuid" )

for Name : xpathdocument( docId , "processModelHaul/process_model_port/pm/meta/name/string-map/pair[1]/value" )

I am getting no response.
when i checked in Community : https://docs.appian.com/suite/help/24.3/fnc_scripting_xpathdocument.html
there also it was mentioned the similar syntax that i am using.
But still i am not getting why the I am getting null as output.

Thanks in advance.