Bug 118592 Report error
please see attached design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/ResultIterator.java
* sequence from the prepared ReportQueryDefn spec. E.g. A group aggregation
	 * is defined to be after_last_row. It would be out of sequence if requested
	 * before having iterated/skipped to the last row of the group. In future
	 * release, this could have intelligence to auto recover and performs
	 * dependent operations to properly evaluate any out-of-sequence result
	 * values.
	 * 
	 * @param dataExpr
	 *            An IBaseExpression object provided in the ReportQueryDefn at
	 *            the time of prepare.
	 * @return The value of the given expression. It could be null.
	 * @throws DataException
	 *             if error occurs in Data Engine
	 */
	public Object getValue( IBaseExpression dataExpr ) throws DataException
	{
		logger.logp( Level.FINE,
				ResultIterator.class.getName( ),
				"getValue",
				"get of value IBaseExpression: " + LogUtil.toString( dataExpr ) );
		checkStarted( );
		
		if ( beforeFirstRow )
		{
			DataException e = new DataException( ResourceConstants.NO_CURRENT_ROW );
			logger.logp( Level.FINE,
					ResultIterator.class.getName( ),
					"getValue",
					"Cursor has no current row.",
					e );