Bug 136553 [regression]Preview error when set invalid group interval.
Description: Preview error when set invalid group interval. Steps to reproduce: 1. Insert a table 2. Add a group on number column, set interval to Year,1 3. Preview 4. Edit group on string column set interval to Prefix,1 5. Preview Expected result: Error msg about invalid group interval. Actual result: Error happened while running the report
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/DataPresentationEngine.java
catch ( IOException ex )
				{
				}
			}
		}
	}
	private StringBuffer keyBuffer = new StringBuffer( );
	protected String getResultID( String pRsetId, long rowId, String queryId )
	{
		keyBuffer.setLength( 0 );
		keyBuffer.append( pRsetId );
		keyBuffer.append( "." );
		keyBuffer.append( rowId );
		keyBuffer.append( "." );
		keyBuffer.append( queryId );
		return (String) rsetRelations.get( keyBuffer.toString( ) );
	}
	protected IResultSet doExecuteQuery( IBaseQueryDefinition query )
	{
		assert query instanceof IQueryDefinition;
		String queryID = (String) queryIDMap.get( query );
		try
		{
			IQueryResults queryResults = null;
			DteResultSet parentResult = (DteResultSet) getResultSet( );
			if ( parentResult != null )
			{
				queryResults = parentResult.getQueryResults( );
			}
			String resultSetID = null;