[android-developers] Sample project for "In app billing" does not work.

TrivialDrive is the official sample project for "In app billing". I can't get the IInAppBillingService class from that project to work. I have imported it into the src directory of my project along with the other utils classes. I have done this with the correct project name. I get a lot of "must override a superclass method" errors in IInAppBillingService. One of the messages is

Multiple markers at this line
- The method consumePurchase(int, String, String) of type IInAppBillingService.Stub.Proxy must override a superclass method
- implements com.android.vending.billing.IInAppBillingService.consumePurchase

The other messages says similar things. I didn't copy "IInAppBillingService.java", only "IInAppBillingService.aidl". Here is a screenshot of how my project looks like:

http://www.mobile-visuals.com/inapp.png

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