Vaadin.ui.CheckBoxGroup Not resolved in eclipse

I have installed vaadin plugin for eclipse 4.3.1 . i need to use Vaadin.ui.CheckBoxGroup but it throws errors as CheckBoxGroup is not available.please help!

My code:

import com.vaadin.ui.CheckBoxGroup;// This Line THrows error

import com.vaadin.ui.ComboBox;

import com.vaadin.ui.DateField;

import com.vaadin.ui.ListSelect;

import com.vaadin.ui.TextField;

import com.vaadin.ui.VerticalLayout;

import com.vaadin.ui.declarative.Design;


Which Vaadin version are you using?

i have vaadin plugin installed with veraion=4.3.1

i have not installed vaadin design framework.

Vaadin Eclipse plugin doesn’t determine the Vaadin version of your project. I’m guessing you might be using Vaadin 7?