Error in SOAP response when webservice is deployed in Weblogic

[p hasini]

The webservice is deployed onto a Weblogic 8.1 server.

WSDL file:

<xs:complexType name="requestTypes">
   <xs:sequence>
        <xs:element name="accountNumber" type="xs:string" minOccurs="0"/>
   </xs:sequence>
</xs:complexType>

SOAP response :

<requestType>
     <accountNumber xsi:nil="true"/>
</requestType> 

If minOccurs=1,then the element should be displayed in the SOAP response even if the element does not have any value.
If minOccurs=0,if the element does not have any value,then the element must not be displayed in the SOAP response.

But as shown in the code,the element is displayed in the SOAP response with xsi:nil attribute set to true,when the element has minOccurs=0 in WSDL file.

Please let me know why is this problem coming.