Copy the below Spec & open the report..your question is answered...
<report xmlns="http://developer.cognos.com/schemas/report/2.0/" expressionLocale="en-us"><!--RS:8.1-->
<modelPath>/content/package[@name='GO Sales and Retailers']/model[@name='model']</modelPath>
<queries>
<query name="Query1">
<source>
<model/>
</source>
<selection><dataItem name="Product line" aggregate="none"><expression>[gosales_goretailers].[Products].[Product line]</expression></dataItem><dataItem name="Product name" aggregate="none"><expression>[gosales_goretailers].[Products].[Product name]</expression></dataItem></selection>
<detailFilters><detailFilter use="optional"><filterExpression>if(?p2? ='S') then ([gosales_goretailers].[Products].[Product line]in ?p1?) else (1=1)</filterExpression></detailFilter></detailFilters></query>
<query name="Query2"><source><model/></source><selection><dataItem name="Product line" aggregate="none"><expression>[gosales_goretailers].[Products].[Product line]</expression></dataItem></selection></query></queries>
<layouts>
<layout>
<reportPages>
<page class="pg" name="Page1">
<pageBody class="pb">
<contents>
<list class="ls" refQuery="Query1">
<style>
<CSS value="border-collapse:collapse"/>
</style>
<listColumns><listColumn><listColumnTitle class="lt"><contents><textItem><dataSource><dataItemLabel refDataItem="Product line"/></dataSource></textItem></contents></listColumnTitle><listColumnBody class="lc"><contents><textItem><dataSource><dataItemValue refDataItem="Product line"/></dataSource></textItem></contents></listColumnBody></listColumn><listColumn><listColumnTitle class="lt"><contents><textItem><dataSource><dataItemLabel refDataItem="Product name"/></dataSource></textItem></contents></listColumnTitle><listColumnBody class="lc"><contents><textItem><dataSource><dataItemValue refDataItem="Product name"/></dataSource></textItem></contents></listColumnBody></listColumn></listColumns></list>
</contents>
</pageBody>
<pageHeader class="ph">
<contents>
<block class="ta">
<contents>
<textItem class="tt">
<dataSource>
<staticValue/>
</dataSource>
</textItem>
</contents>
</block>
</contents>
<style>
<CSS value="padding-bottom:10px"/>
</style>
</pageHeader>
<pageFooter class="pf">
<contents>
<table class="tb">
<tableRows>
<tableRow>
<tableCells>
<tableCell>
<contents>
<textItem>
<dataSource>
<reportExpression>AsOfDate()</reportExpression>
</dataSource>
</textItem>
</contents>
<style>
<CSS value="vertical-align:top;text-align:left;width:25%"/>
</style>
</tableCell>
<tableCell>
<contents>
<textItem>
<dataSource>
<staticValue>- </staticValue>
</dataSource>
</textItem>
<textItem>
<dataSource>
<reportExpression>PageNumber()</reportExpression>
</dataSource>
</textItem>
<textItem>
<dataSource>
<staticValue> -</staticValue>
</dataSource>
</textItem>
</contents>
<style>
<CSS value="vertical-align:top;text-align:center;width:50%"/>
</style>
</tableCell>
<tableCell>
<contents>
<textItem>
<dataSource>
<reportExpression>AsOfTime()</reportExpression>
</dataSource>
</textItem>
</contents>
<style>
<CSS value="vertical-align:top;text-align:right;width:25%"/>
</style>
</tableCell>
</tableCells>
</tableRow>
</tableRows>
<style>
<CSS value="border-collapse:collapse;width:100%"/>
</style>
</table>
</contents>
<style>
<CSS value="padding-top:10px"/>
</style>
</pageFooter>
</page>
</reportPages>
<promptPages><page class="pp" name="Prompt Page1">
<pageHeader class="hp">
<contents>
<block class="ta">
<contents>
<textItem class="tt">
<dataSource>
<staticValue/>
</dataSource>
</textItem>
</contents>
</block>
</contents>
</pageHeader>
<pageBody class="py">
<contents><table class="tb"><tableRows><tableRow><tableCells><tableCell><contents/></tableCell><tableCell><contents><selectValue parameter="p2" autoSubmit="true" selectValueUI="radioGroup"><defaultSelections><defaultSimpleSelection>S</defaultSimpleSelection></defaultSelections><selectOptions><selectOption useValue="H"><displayValue>Hide</displayValue></selectOption><selectOption useValue="S"><displayValue>Show</displayValue></selectOption></selectOptions></selectValue>
</contents></tableCell></tableCells></tableRow><tableRow><tableCells><tableCell><contents/></tableCell><tableCell><contents><selectValue parameter="p1" refQuery="Query2" selectValueUI="listBox" multiSelect="true" range="false" required="true" cascadeOn="p2"><useItem refDataItem="Product line"/></selectValue>
</contents></tableCell></tableCells><conditionalStyles><conditionalStyleCases refVariable="Boolean1"><conditionalStyle refVariableValue="1"><CSS value="display:none"/></conditionalStyle></conditionalStyleCases><conditionalStyleDefault/></conditionalStyles></tableRow><tableRow><tableCells><tableCell><contents/></tableCell><tableCell><contents/></tableCell></tableCells></tableRow></tableRows><style><CSS value="border-collapse:collapse;width:100%"/></style></table></contents>
</pageBody>
<pageFooter class="fp">
<contents>
<promptButton type="cancel" class="bp">
<contents/>
</promptButton>
<promptButton type="back" class="bp">
<contents/>
</promptButton>
<promptButton type="next" class="bp">
<contents/>
</promptButton>
<promptButton type="finish" class="bp">
<contents/>
</promptButton>
</contents>
</pageFooter>
</page>
</promptPages></layout>
</layouts>
<reportVariables><reportVariable type="boolean" name="Boolean1">
<reportExpression>ParamValue('p2')='H'</reportExpression>
<variableValues>
<variableValue value="1"/>
</variableValues>
</reportVariable>
</reportVariables></report>