JAX-RPC - deserialization error: unexpected XML reader state.

[Scott Lynch]

java.rmi.RemoteException: Runtime exception; nested exception is: 
deserialization error: unexpected XML reader state. expected: END but found: START: errorCode
at com.sun.xml.rpc.client.StreamingSender._handleRuntimeExceptionInSend(StreamingSender.java:248)
at com.sun.xml.rpc.client.StreamingSender._send(StreamingSender.java:230)

I know that "errorCode" is one of the values in my defined response structure, which (in WSDL) looks like this:

<xsd:complexType name="ImageValueObject">
-
<xsd:sequence>
<xsd:element type="xsd:int" name="errorCode" minOccurs="1" maxOccurs="1">
     </xsd:element>
<xsd:element type="xsd:string" name="errorDesc" minOccurs="1" nillable="true" maxOccurs="1">
     </xsd:element>
<xsd:element type="xsd:base64Binary" name="image" minOccurs="1" nillable="true" maxOccurs="1">
     </xsd:element>
<xsd:element type="xsd:string" name="irn" minOccurs="1" nillable="true" maxOccurs="1">
     </xsd:element>
</xsd:sequence>
</xsd:complexType>

Does anyone know what could be causing this? (bad response from server?)