jasperreports subreport with multiple columns does not print properly - jasper-reports

Question

I am new to Jasper reports. I have a master report that needs to print text in 3 columns. This text is dynamic and very long (about 2 pages). By set columnCount="3", the report is print as I expected (2 pages with 3 columns in each page). However I need to insert title on top of these 3 columns of first page only. If I just add textField on top of them. The title would be overlapped by text from 2nd column. So, I add subreport under title instead and set columnCount="3" in subreport instead. However, when I generate report this time it print everything in first column of every page. Please suggest what is wrong with my configuration. Thanks in advance.
master report
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="Master" pageWidth="612" pageHeight="792" columnWidth="552" leftMargin="30" rightMargin="30" topMargin="0" bottomMargin="10">
<property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
<parameter name="Title"/>
<parameter name="Content"/>
<queryString>
<![CDATA[]]>
</queryString>
<background>
<band splitType="Stretch"/>
</background>
<detail>
<band height="782" splitType="Stretch">
<textField>
<reportElement x="0" y="20" width="180" height="25"/>
<textFieldExpression><![CDATA[$P{Title}]]></textFieldExpression>
</textField>
<subreport>
<reportElement x="0" y="50" width="552" height="732"/>
<subreportParameter name="Content">
<subreportParameterExpression><![CDATA[$P{Content}]]></subreportParameterExpression>
</subreportParameter>
<dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.JREmptyDataSource()]]></dataSourceExpression>
<subreportExpression><![CDATA["subreport.jasper"]]></subreportExpression>
</subreport>
</detail>
</jasperReport>
subreport
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="Subreport" pageWidth="552" pageHeight="732" columnCount="3" columnSpacing="6" columnWidth="180" leftMargin="0" rightMargin="0" topMargin="0" bottomMargin="0"whenNoDataType="AllSectionsNoDetail">
<parameter name="Content"/>
<summary>
<band height="732" splitType="Stretch">
<textField textAdjust="StretchHeight">
<reportElement x="0" y="0" width="180" height="20"/>
<textFieldExpression><![CDATA[$P{Content}]]></textFieldExpression>
</textField>
</summary>
</jasperReport>