Using Google Play Quests in Unity 4?

Is it possible to use google play games quests in versions of unity below 5?
I am using Unity 4.5.2f1, and am using the latest google play games plugin. When i add this code to show quests:

PlayGamesPlatform.Instance.Quests.ShowAllQuestsUI((QuestUiResult result, IQuest quest, IQuestMilestone milestone) => {
				// ...});

the scipts referenced(QuestUiResult,IQues and IQuesMilestone) don’t exist in the current context.

Am i doing something wrong?

Any help is greatly appreciated, thanks.

Hey @12boulla

Are you sure you have declared this line at the beginning of your code ?

using GooglePlayGames.BasicApi.Quests;