getting AWS DynamoDB Timestamp in Android SDK

I'm to the AWS Android DynamoDB SDK and lately I encounter a problem and still caot fix it. When trying to get the 'Created' value of my DynamoDB I get the following error message:" Expected S in value {N: 1449848553974,} ". What I know so far from the AWS documentation is that 'N' stand for the Datatype Number.

Here is the code of the Class:

@DynamoDBTable(tableName = "dev.records_log")
public class Record
{
private Number created;

@DynamoDBAttribute(attributeName = "created")
@DynamoDBMarshalling(marshallerClass = TimeStampConverter.class)
public Number getTimestamp_created() 
{
   retu created;
}

@DynamoDBMarshalling(marshallerClass = TimeStampConverter.class)
 public void setRecord_created(Number created) {
        this.created = created;
    }

Hope someone could help me out with this issue. I browse through the inteet but with no positive results.

Thanks in advance.