DataSink Report - Parameter not found

I have been trying to capture the request and response payloads of a RESTful webservice in the SOAP-UI test runs, via. the use of DataSink.

In order to visualize, the set up is as below:

Properties in the DataSink (as Subreport) have also been set as seen below :

Next, I created a subReport named it UniRestService. Below is the code :

SubReport Name: UniRestService

ReportType: TestCase

Scope: Project

DataSource: Data Sink

<jasperReport xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="report name" language="groovy" pageWidth="535" pageHeight="842" columnWidth="535" leftMargin="0" rightMargin="0" topMargin="0" bottomMargin="0" xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <template>"../../styles.jrtx"</template>
   
   <field name="sessionId" class="java.lang.String"/>
   <field name="request" class="java.lang.String"/>
   <field name="response" class="java.lang.String"/>
   <columnHeader>
      <band height="37">
         <staticText>
            <reportElement style="SmallHeader" x="0" y="0" width="535" height="34"/>
            <textElement textAlignment="Left" verticalAlignment="Middle">
               <font size="14" isBold="true" isUnderline="true"/>
            </textElement>
            <text>API Execution Details</text>
         </staticText>
      </band>
   </columnHeader>
   <detail>
      <band height="120">
         <staticText>
            <reportElement x="0" y="0" width="67" height="20"/>
            <textElement>
               <font isBold="true" isUnderline="true"/>
            </textElement>
            <text>Session ID</text>
         </staticText>
         <textField isStretchWithOverflow="true">
            <reportElement x="67" y="0" width="100" height="20"/>
            <textFieldExpression>$F{sessionId}</textFieldExpression>
         </textField>
         <staticText>
            <reportElement x="0" y="20" width="67" height="20"/>
            <textElement>
               <font isBold="true" isUnderline="true"/>
            </textElement>
            <text>Request :</text>
         </staticText>
         <textField isStretchWithOverflow="true">
            <reportElement x="67" y="20" width="468" height="20"/>
            <textFieldExpression>$F{request}</textFieldExpression>
         </textField>
         <staticText>
            <reportElement x="0" y="40" width="67" height="20"/>
            <textElement>
               <font isBold="true" isUnderline="true"/>
            </textElement>
            <text>Response:</text>
         </staticText>
         <textField isStretchWithOverflow="true">
            <reportElement x="67" y="40" width="468" height="20"/>
            <textFieldExpression>$F{response}</textFieldExpression>
         </textField>
      </band>
   </detail>
</jasperReport>

Next, I created the the main report named : test, Below is the configuration screenshot:

And the correponding code is below :

<jasperReport xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="ReportTemplate" language="groovy" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="30" bottomMargin="30" xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <template>"../../styles.jrtx"</template>
   <!--FIELDS & PARAMS-->
   <title>
      <band height="70">
         <textField>
            <reportElement x="159" y="13" width="229" height="42"/>
            <textElement>
               <font size="26"/>
            </textElement>
            <textFieldExpression class="java.lang.String">$F{name} + " Report"</textFieldExpression>
         </textField>
      </band>
   </title>
   <pageHeader>
      <band/>
   </pageHeader>
   <detail>
      <band height="122">
         <!--SUBREPORTS UNDER HERE-->
         <subreport isUsingCache="true">
            <reportElement positionType="Float" isPrintRepeatedValues="false" x="0" y="0" width="500" height="30"/>
            <dataSourceExpression><![CDATA[$P{dataSink}]]></dataSourceExpression>
            <subreportExpression><![CDATA["subreport:UniRestService"]]></subreportExpression>
         </subreport>
      </band>
   </detail>
</jasperReport>

I have also tried with the the following dataSourceExpression in the code snippet above :

            <dataSourceExpression><$P{dataSink}></dataSourceExpression>
            <subreportExpression><"subreport:UniRestService"></subreportExpression>

In either cases, I get the following error, from the error.log.

Sun Nov 01 10:44:10 EST 2015:ERROR:net.sf.jasperreports.engine.design.JRValidationException: Report design not valid : 
	 1. Parameter not found : dataSink
   net.sf.jasperreports.engine.design.JRValidationException: Report design not valid : 
   	 1. Parameter not found : dataSink
   	at net.sf.jasperreports.engine.design.JRAbstractCompiler.verifyDesign(JRAbstractCompiler.java:258)
   	at net.sf.jasperreports.engine.design.JRAbstractCompiler.compileReport(JRAbstractCompiler.java:140)
   	at net.sf.jasperreports.engine.JasperCompileManager.compileReport(JasperCompileManager.java:215)
   	at com.eviware.soapui.reporting.engine.jasper.GenerateJasperReport.createReport(SourceFile:409)
   	at com.eviware.soapui.reporting.engine.jasper.GenerateJasperReport$ReportFillWorker.construct(SourceFile:382)
   	at com.eviware.soapui.support.swing.SwingWorkerDelegator.construct(SwingWorkerDelegator.java:46)
   	at com.eviware.soapui.support.swing.SwingWorker$2.run(SwingWorker.java:131)
   	at java.lang.Thread.run(Unknown Source)

Any help is much appreciated here.

Thanks in advance.