Mapping XML

Assume I have a class “Response” defined as follows:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
        "field",
        "error"
})
@XmlRootElement(name = "Response",namespace="http://www.calculator.com/CalculateNetAmount")
public class Response{
  @XmlElement(required = true, namespace="http://www.calculator.com/CalculateNetAmount")
  protected String field;
  @XmlElement(required = true, namespace="http://www.calculator.com/CalculateNetAmount")
  protected String error;

  public String getField() { return field; }

  public void setField(String value) { this.field = value; }

  public String getError() { return error; }

  public void setError(String value) { this.error = value; }
}

I’m trying to map this XML:

<cal:Response xmlns:cal="http://www.calculator.com/CalculateNetAmount">
      <cal:field>stringField</cal:field>
      <cal:error>stringError</cal:error>
</cal:Response>

in the following way:
Response response= XML(xmlInput).mapTo(Response.class);

Notwithstanding the object being created, its parameters strings are empty / null.
What’s wrong in here?