report preview flashes and disappears - jasper-reports

Question

When i'm trying to preview the data in IReports by clicking the preview tab, it is just flashing and going back, but i'm unable to see the data.
Below is my XML.
<?xml version="1.0" encoding="UTF-8"?>
<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="report5" language="groovy" pageWidth="842" pageHeight="595" orientation="Landscape" columnWidth="802" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="b8a981bc-ae9b-4fcf-8400-f9ecea0567f2">
<property name="ireport.zoom" value="1.0"/>
<property name="ireport.x" value="0"/>
<property name="ireport.y" value="0"/>
<style name="Crosstab Data Text" hAlign="Center"/>
<queryString>
<![CDATA[SELECT
`Date assigned` AS Date_assigned,
Units,
`Assigned to PS` AS Assigned_to_PS
FROM
[Sheet1$]
]]>
</queryString>
<field name="Date_assigned" class="java.sql.Timestamp"/>
<field name="Units" class="java.lang.Double"/>
<field name="Assigned_to_PS" class="java.lang.String"/>
<group name="Date_assigned">
<groupExpression><![CDATA[$F{Date_assigned}]]></groupExpression>
</group>
<background>
<band splitType="Stretch"/>
</background>
<title>
<band height="79" splitType="Stretch"/>
</title>
<pageHeader>
<band height="35" splitType="Stretch"/>
</pageHeader>
<columnHeader>
<band height="61" splitType="Stretch"/>
</columnHeader>
<detail>
<band height="125" splitType="Stretch">
<crosstab>
<reportElement uuid="db476b5b-d93f-4819-a8f6-174bfc88c9b7" x="0" y="0" width="802" height="125"/>
<rowGroup name="Date_assigned" width="70" totalPosition="End">
<bucket class="java.util.Date">
<bucketExpression><![CDATA[$F{Date_assigned}]]></bucketExpression>
</bucket>
<crosstabRowHeader>
<cellContents backcolor="#F0F8FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<textField>
<reportElement uuid="cb26a0e2-7fa8-4124-be7f-f91e491801f7" style="Crosstab Data Text" x="0" y="0" width="70" height="25"/>
<textElement/>
<textFieldExpression><![CDATA[$V{Date_assigned}]]></textFieldExpression>
</textField>
</cellContents>
</crosstabRowHeader>
<crosstabTotalRowHeader>
<cellContents backcolor="#BFE1FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<staticText>
<reportElement uuid="c97deff9-a499-4330-aa84-baf20315a1de" x="0" y="0" width="70" height="25"/>
<textElement textAlignment="Center" verticalAlignment="Middle"/>
<text><![CDATA[Total Date_assigned]]></text>
</staticText>
</cellContents>
</crosstabTotalRowHeader>
</rowGroup>
<columnGroup name="Assigned_to_PS" height="30" totalPosition="End">
<bucket class="java.lang.String">
<bucketExpression><![CDATA[$F{Assigned_to_PS}]]></bucketExpression>
</bucket>
<crosstabColumnHeader>
<cellContents backcolor="#F0F8FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<textField>
<reportElement uuid="7e26e7de-b54f-4490-9ea1-b087247e9c06" style="Crosstab Data Text" x="0" y="0" width="50" height="30"/>
<textElement/>
<textFieldExpression><![CDATA[$V{Assigned_to_PS}]]></textFieldExpression>
</textField>
</cellContents>
</crosstabColumnHeader>
<crosstabTotalColumnHeader>
<cellContents backcolor="#BFE1FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<staticText>
<reportElement uuid="86c2ceb5-b2d2-4cc7-953e-0c039e807ec1" x="86" y="0" width="50" height="30"/>
<textElement textAlignment="Center" verticalAlignment="Middle"/>
<text><![CDATA[Total Assigned_to_PS]]></text>
</staticText>
</cellContents>
</crosstabTotalColumnHeader>
</columnGroup>
<measure name="UnitssMeasure" class="java.lang.Double" calculation="Sum">
<measureExpression><![CDATA[$F{Unitss}]]></measureExpression>
</measure>
<crosstabCell width="120" height="38">
<cellContents>
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<textField>
<reportElement uuid="7729498a-0309-4052-a002-e58592da972b" style="Crosstab Data Text" x="0" y="0" width="50" height="25"/>
<textElement/>
<textFieldExpression><![CDATA[$V{UnitssMeasure}]]></textFieldExpression>
</textField>
</cellContents>
</crosstabCell>
<crosstabCell width="120" height="61" rowTotalGroup="Date_assigned">
<cellContents backcolor="#BFE1FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<textField>
<reportElement uuid="35ba6c60-5505-4eba-be7b-8627a9516c7d" style="Crosstab Data Text" x="0" y="0" width="50" height="25"/>
<textElement/>
<textFieldExpression><![CDATA[$V{UnitssMeasure}]]></textFieldExpression>
</textField>
</cellContents>
</crosstabCell>
<crosstabCell width="136" height="38" columnTotalGroup="Assigned_to_PS">
<cellContents backcolor="#BFE1FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<textField>
<reportElement uuid="c260e58c-5377-4582-bdfe-59a3f337feee" style="Crosstab Data Text" x="86" y="0" width="50" height="25"/>
<textElement/>
<textFieldExpression><![CDATA[$V{UnitssMeasure}]]></textFieldExpression>
</textField>
</cellContents>
</crosstabCell>
<crosstabCell width="136" height="61" rowTotalGroup="Date_assigned" columnTotalGroup="Assigned_to_PS">
<cellContents backcolor="#BFE1FF" mode="Opaque">
<box>
<pen lineWidth="0.5" lineStyle="Solid" lineColor="#000000"/>
</box>
<textField>
<reportElement uuid="468233cd-75a6-4278-ba3f-de35032a5459" style="Crosstab Data Text" x="86" y="0" width="50" height="25"/>
<textElement/>
<textFieldExpression><![CDATA[$V{UnitssMeasure}]]></textFieldExpression>
</textField>
</cellContents>
</crosstabCell>
</crosstab>
</band>
</detail>
<columnFooter>
<band height="45" splitType="Stretch"/>
</columnFooter>
<pageFooter>
<band height="54" splitType="Stretch"/>
</pageFooter>
<summary>
<band height="42" splitType="Stretch"/>
</summary>
</jasperReport>
This is actually a pivot table from excel data source, please let me know how do i preview it. And also i'm not getting any errors.
expected output is
Amreen Anirudh Anand Total
7/1/2013 158 158
7/2/2013 23 23
7/3/2013 152 748 900
7/4/2013
7/5/2013
7/6/2013 435 435
7/7/2013 170 170
7/8/2013 66 66
7/9/2013 33 33 66
Total 1037 748 33 1818
Thanks