wso2 esb sending dss NumberFormatException with blank input

I have a proxy inside wso2 esb. I used call and I want to send response from call to my outSequence. But it gives me Dss error.I do not use dss at all. Can anyone tell why this error happens and how can I solve this? this is my proxy code:

<proxy xmlns="http://ws.apache.org/ns/synapse"
   name="FinaltestProxy"
   startOnLoad="true"
   statistics="disable"
   trace="enable"
   transports="https,http,vfs">
<target>
  <inSequence>
        <input type="text"/>
        <output type="xml"/>
     </smooks>
     <iterate attachPath="//csv-set"
              continueParent="true"
              expression="//csv-set/search"
              preservePayload="true"
              sequential="true">
        <target>
           <sequence>
              <call>
                 <endpoint>
                    <address format="soap11"
                             uri="MyEndpoint"/>
                 </endpoint>
              </call>
              <respond/>
           </sequence>
        </target>
     </iterate>
  </inSequence>
  <outSequence>
     <property name="OUT_ONLY" value="true"/>
     <aggregate>
        <completeCondition>
           <messageCount max="100000" min="0"/>
        </completeCondition>
        <onComplete xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope"
                    expression="//Guest">
           <log level="full"/>
           <send>
              <endpoint name="FileEpr">
                 <address format="soap11"
                          uri="MyEndpoint"/>
                 <property name="ContentType" scope="axis2" value="text/xml"/>
              </endpoint>
           </send>
        </onComplete>
     </aggregate>
  </outSequence>
</target>
 /* some code*/
</proxy>

and this is my Error:

DS Code: DATABASE_ERROR
Nested Exception:-
javax.xml.stream.XMLStreamException: DS Fault Message: Error in    'SQLQuery.processNormalQuery'
DS Code: DATABASE_ERROR
Source Data Service:-
Name: GuestIdentityService
Location: /ss.dbs
Description: N/A
Default Namespace: http://soa.ut.ac.ir/GuestIdentityService
Current Request Name: searchGuestIdentity
Current Params: {ID=}
Nested Exception:-
java.lang.NumberFormatException: For input string: ""

there was a blank line in my input and that cause the problem.