compass error：File to import not found or unreadable

error:

 error sass/common.scss (Line 2: File to import not found or unreadable: base/_head.scss.
Load paths:
  Compass::SpriteImporter
  F:/newpagebao/happybao/stc/sass
  C:/Ruby22/lib/ruby/gems/2.2.0/gems/compass-core-1.0.3/stylesheets)

为什么路径总是找不到？

---

改用相对路径：

@import "../base/_head.scss";