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
throw new EngineException( "Invalid Columns" );
				}
			}
		}
		else
		{
			if ( exprs.size( ) <= 0 )
			{
				throw new EngineException( "Can't exported data in groups" );
			}
			else
			{
				selectedColumns = new String[exprs.size( )];
				Iterator iter = exprs.iterator( );
				
				for ( int i = 0; i < selectedColumns.length; i++ )
				{
					IScriptExpression expr = (IScriptExpression) iter.next( );
					selectedColumns[i] = expr.getText( );
				}
			}
		}
 	}
	private Collection getValueExpressions( IBaseQueryDefinition query )
	{
		ArrayList valueExprs = (ArrayList)mapQueryToValueExprs.get( query );
		return valueExprs;
	}
}