How to set an optional param on a Report Definition

Hi guys. I'm trying to add optional parameters to my Report Definition in the HMC in order to filter my results.

 <attribute generate="false" autocreate="true" qualifier="product" type="Product" metatype="ViewAttributeDescriptor">
             <persistence type="jalo" qualifier=""/>
             <modifiers read="true" write="false" search="true" encrypted="false" optional="true" removable="true" initial="false" unique="false" private="false" partof="false"/>
             <custom-properties>
                 <property name="param">
                     <value>
 Boolean.TRUE
                     </value>
                 </property>
                 <property name="position">
                     <value>
 new Integer(0)
                     </value>
                 </property>
             </custom-properties>
         </attribute>

I've set the optional modifier to true, however when I run my report without selecting a product I get an exception stating that "You must fill out all search conditions".

Any advice would be much appreciated.

Regards

Dewaldt