Bug 124251 the data cann't been exported.
Description: the data cann't been exported. Steps to reproduce: 1. new a report 2. new a datasource and a data set(DS_A) 3. use an external library 4. drag a table to the report layout from the imported library 5. insert an another table into the layout of the report and bind the data set(DS_A) 6. preview in the 'Web Viewer' and export the data Actual result: The data can been exported. Expect result: The data can been exporteded
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTask.java
metaData = new ResultMetaData( null,
						selectedColumns );
				resultMetaList.add( metaData );
			}
		}
		return resultMetaList;
	}
	
	public List getResultSetList( ) throws EngineException
	{	
		if (resultMetaList == null) 
		{
			prepareMetaData( );
			resultMetaList = new ArrayList();
			String dispName = null;
			if( instanceId != null )
			{
				ReportItemDesign reportItem = (ReportItemDesign)report.getReportItemByID( 
						instanceId.getComponentID( ) );
				IBaseQueryDefinition query = reportItem.getQuery( );
				dispName = (String)mapQueryToDispName.get( query ); 
				
				addToResultSetList( query, dispName );
			}
			else
			{
				Set keySet = mapQueryToDispName.keySet( );
				Iterator keyIter = keySet.iterator( );
				while( keyIter.hasNext( ))
				{