I'm using Unity 3.5x and Vuforia 1.5 version.
Today I created a new device database, downloaed it as a Unity package, and imported it in the Unity. Also, I modified ARCamera's Data Set Load Behaviour to load the data set and activated it in the Unity inspector. I selected Data Set and Image Target properly in the Image Target Behaviour of ImageTarget's inspector.
When I run the application, I got the error like below. (it is Eclipse's LogCat message. My Unity project is integrated into my Eclipse Android project.)