Problem with UI Button calling function [4.6 UI]

I’ve created a toggle list, where each toggle changes the unit to create, like an RTS. However, the function I want to use doesn’t show up in the event list for reasons I don’t know. Here’s the code:

//Unit to deploy
public Soldier UnitToDeploy;

//List of deployable units
[System.Serializable]
public class Soldier {
	public GameObject soldier;
	public int soldierCost;
}

public Soldier Riflemen, SpecOps, Gunner, Sniper, Support;

//public void to change the UnitToDeploy
public void ChooseUnit(Soldier soldier)
{
    UnitToDeploy = soldier;
}

Does anyone have any ideas why I can’t even select the ChooseUnit function?

The new UI events can only call public functions with primitive parameters and no return, for exemple: public void ChooseUnit(int soldierID)
Take a look at this video here: http://unity3d.com/pt/learn/tutorials/modules/beginner/ui/ui-button