Android pull to Refresh 导入出错？

今天在导入 PuultoResfresh 的时候老是出错.

error:

[2014-09-28 10:04:44 - library] Unable to resolve target 'android-16'
[2014-09-28 10:04:59 - PullToRefreshListFragment] Unable to resolve target 'android-16'
[2014-09-28 10:04:59 - PullToRefreshListFragment] Unable to resolve target 'android-16'

我换了一个工作空间就能够了。