In our instance we are using custom basemaps that reflect our states boundaries and needs. When I add that property; I get this error returned to me:
Map.setBasemap: Unable to find basemap definition for: "streetBasemap". Try one of these: streets,satellite,hybrid,terrain,topo,gray,dark-gray,oceans,national-geographic,osm,dark-gray-vector,gray-vector,streets-vector,topo-vector,streets-night-vector,streets-relief-vector,streets-navigation-vector.
Is this dependent on the Title ("Streets") of the map; or the name of the basemap-object I created when instantiating my gallery as defined in JavaScript?