Unable to use ActionBarSherlock library

I have Created a new android project from existing source(ActionBarSherlock library) with API 15. I added this library to my project(Project properties -> android -> library-> add ->com_actionbarsherlock ->apply ->ok).But When I again see (Project properties -> android -> library->) com_actionbarsherlock is showing red color cross.So, I am unable to import the library classes.I am really struggling with this.
Any help would be appreciate.

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