Thumbnail view for Library copied from Asset Library does not work

Hello ,

I created list definition based on Assed Library (I copied files from \15\TEMPLATE\FEATURES\AssetLibrary\AssetLibrary ) - I reused schema.xml and other files.
Then I added my new custom content type.
The problem is following:  thumbnail view does not work now ( "/AssetLibraryDemo/Forms/Thumbnails.aspx" )
I don't have any javascript errors and any specific error in ULS log.
Can you give me advice, why thumbnail view has stopped working?