XML : JAXB unmarshall: where does ElementNSImpl come from?

hen I unmarshall a certain object I don't get back the type of the object but the type ElementNSImpl that appears to have my data in it but why won't JAXB unmarshall it into my JAXB classes?

  @XmlAccessorType(XmlAccessType.FIELD)  @XmlType(name = "Asset", propOrder = {      "platformContentOrFeatureContentOrAirspace",      ...  })  @XmlSeeAlso({      ...  })  public abstract class Asset {      @XmlElements({          @XmlElement(name = "PlatformContent", type = AnyPlatform.class),          @XmlElement(name = "FeatureContent", type = AnyFeature.class),          @XmlElement(name = "Airspace", type = Airspace.class)      })      protected Object platformContentOrFeatureContentOrAirspace;        ...        public Object getPlatformContentorFeatureContentorAirspace(){          return platformContentOrFeatureContentOrAirspace;      }      ...  }    

Here is a schema fragment:

  <complexType name="AssetBaseType">      <complexContent>        <restriction base="{http://www.w3.org/2001/XMLSchema}anyType">          <sequence>            <choice minOccurs="0">              <element name="PlatformContent" type="temp:TargetNamespaceURI}AnyPlatform"/>              <element name="FeatureContent" type="{temp:TargetNamespaceURI}AnyFeature"/>              <element ref="{temp:TargetNamespaceURI}Airspace"/>            </choice>          </sequence>        </restriction>      </complexContent>    </complexType>