How to solve "Directly link to required .class files" error in android?

I am creating an android application where I am using a chat model. There is a WebSite name like QuickBlox where all server parts are descriptors. I am using it for my application. They also provide Android sample code, I import the sample code and add all the libs and jars that should run this project.

Now the problem is in one of my classes there is an error "indirectly references required .class files". What dose does this mean and how to fix this problem, can someone help me in solving this problem.

Below is my class code -

public class UsersAdapter extends BaseAdapter {

private List<QBUser> dataSource;
private LayoutInflater inflater;
private List<QBUser> selected = new ArrayList<QBUser>();

public UsersAdapter(List<QBUser> dataSource, Context ctx) {
    this.dataSource = dataSource;
    this.inflater = LayoutInflater.from(ctx);
}

public List<QBUser> getSelected() {
    return selected;
}

@Override
public int getCount() {
    return dataSource.size();
}

@Override
public Object getItem(int position) {
    return dataSource.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
        convertView = inflater.inflate(R.layout.list_item_user, null);
        holder = new ViewHolder();
        holder.login = (TextView) convertView.findViewById(R.id.userLogin);
        holder.add = (CheckBox) convertView.findViewById(R.id.addCheckBox);
        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }
    final QBUser user = dataSource.get(position);
    if (user != null) {
        holder.login.setText(user.getLogin());
        holder.add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if ((((CheckBox) v).isChecked())) {
                    selected.add(user);
                } else {
                    selected.remove(user);
                }
            }
        });
        holder.add.setChecked(selected.contains(user));
    }
    return convertView;
}

private static class ViewHolder {
    TextView login;
    CheckBox add;
}

      

        
        
        
      

    

}

This is the documentation code for Android - [ http://quickblox.com/developers/Android] [[1 ]