Expandable Basemap Gallery problem (no basemaps available)

[TubaKumbara]

Hello.

I've adding some basemaps to my sceneview

var myBasemap;

for each .............. {

     myBasemap.baseLayers.add( new TileLayer ({ url: myurl, title: mytitle, visible: true  }))

}

var mymap = new Map ({ basemap: myBasemap, layers: [ mylayers ] });;

var mysceneview = new SceneView (................... map: mymap)

I'm seeing my basemap on sceneview when i started program. But cannot create basemap gallery. 

I'm getting "No Basemaps Available" message. 

var basemapGal = new BasemapGallery ({

     view: mysceneview,

     container: document.createElement("div")

})

var bgExpand = new Expand({ view: mysceneview, content: basemapGal.container, expandIconClass: "esri-icon-basemap" }); // view.ui.add(bgExpand, "top-right");

thanks inadvance.

[TubaKumbara · Accepted solution]

ok. i found a solution that basemapgallerry needs source property as an array which has layer list