为什么备份管理器没有完成我的备份？

Question

    public class MyBackupAgent extends BackupAgentHelper {
        static final String DB_FILE_NAME = "name";
        static final String DB_BACKUP_KEY = "key";

        @Override
        public void onCreate() {
            FileBackupHelper dbs = new FileBackupHelper(this, getFilesPath());
            addHelper(DB_BACKUP_KEY, dbs);
        }

        private String getFilesPath() {
            File path = getDatabasePath(DB_FILE_NAME);
            return path.getAbsolutePath();
        }
}

报告的输出是：

04-27 21:54:13.681: V/BackupManagerService(1087): addPackageParticipantsLocked: #1
04-27 21:54:13.681: I/BackupManagerService(1087): Scheduling backup for new app my.package
04-27 21:54:13.681: D/BackupManagerService(1087): Now staging backup of my.package
04-27 21:55:11.621: D/BackupManagerService(1087): couldn't find params for token 0

有什么问题？