REST receiver dynamic url pattern

Hey All,

In REST receiver adapter, in URL pattern, http://test/Param1={var1}

In Pattern Variable replacement:

Value source XPath expression

Pattern element name var1

XPath expression //MT_test/field1

Request msg data something like

<MT_test>

<field1>1</field1>

<field2>2</field2>

</MT_test>

In comm channel monitoring, it shows in log that Calling server: GET http://test/Param1=

So why is the value of var1 not showing in the log? Thx.