CS0246: The type or namespace name 'Cascade' could not be found

[gstadter]

Line 2: @using Cascade.Bootstrap.Models;

fresh, clean install of Orchard v.1.10.2.0, first action is adding Cascade Bootstrap theme Version: 3.3.5.10.
When I preview the theme, I get the error:
CS0246: The type or namespace name 'Cascade' could not be found