Bug 135465 [smoke]An error occurred when new a casading Parameter
Description: An error occurred when new a casading Parameter Step to reproduce: 1.new a sample db data source and data set 2.New a cascading parameter group, named "gp1", 3.select the data set, then create two cascading parameters, one is row["customernumber"], named p1; the other is row["customername"] Actual result; error message occurred repeatly
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
formatPattern = null;
			}
			else
			{
				formatCategroy = getCategroy( selectedParameter.getFormat( ) );
				formatPattern = getPattern( selectedParameter.getFormat( ) );
			}
		}
		updateFormatField( );
	}
	private String getInputDisplayName( )
	{
		String displayName = null;
		if ( DesignChoiceConstants.PARAM_CONTROL_LIST_BOX.equals( selectedParameter.getControlType( ) ) )
		{
			if ( selectedParameter.isMustMatch( ) )
			{
				displayName = DISPLAY_NAME_CONTROL_COMBO;
			}
			else
			{
				displayName = DISPLAY_NAME_CONTROL_LIST;
			}
		}
		return displayName;
	}
	private IChoiceSet getFormatChoiceSet( String type )
	{
		IChoiceSet choiceSet = null;
		if ( DesignChoiceConstants.PARAM_TYPE_STRING.equals( type ) )