TileGrid setTileConstructor

Please help me the setTileConstructor is color red and when i hover it says cannot resolve method.

GWT.create(GalleryTileMetaFactory.class);
Date dateToday = new Date ();
Date dateYesterday = new Date();
String dateCriteria = DateTimeFormat.getShortDateFormat().format(dateToday)+ " AND " + DateTimeFormat.getShortDateFormat().format(dateYesterday);
GalleryDS galleryDS = new GalleryDS(dateCriteria);

TileGrid tileGrid = new TileGrid();
tileGrid.setTileWidth(250);
tileGrid.setTileHeight(150);
tileGrid.setHeight100();
tileGrid.setWidth100();
tileGrid.setDataSource(galleryDS);
tileGrid.setAutoFetchData(true);
tileGrid.setTileConstructor(GalleryTile.class.getName());
tileGrid.draw();