Where to store the actual library project does not matter, as long as you use a relative link to reference it. Check out the Library Projects - Development considerations:
Library project storage location
There are no specific requirements on where you should store a library project, relative to a dependent application project, as long as the application project can reference the library project by a relative link. What is important is that the main project can reference the library project through a relative link.
You should always use the Eclipse ADT plugin to select and set up Library Project Reference, i.e. right-click project -> Properties -> Android -> Add, then in the opened Project Selection window, select the Library Project list here (of cause you should import them in the same Eclipse workspace as your Main Project). This will add a android.library.reference using relative path into project.properties as well as show relative path in the Android preference window:
android.library.reference.2=../../../../../Documents and Settings/yorkw/Desktop/JakeWharton-Android-ViewPagerIndicator-f09acb0/library
If you directly alter it using absolute path from project.properties as below:
android.library.reference.1=C:\Documents and Settings\yorkw\Desktop\JakeWharton-Android-ViewPagerIndicator-f09acb0\library
Then after Eclipse refresh your project, you get the exact error described in your question, see my screenshot below:
Hope this helps.
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