I'm taking a CSIS 1410 Class, and as part of an assignment, I needed to create an enum, Voltage. Then, I had to create a class that uses the enum as a parameter, but when attempting to use the reference variable voltage (lowercase v), it gives me error "voltage cannot be resolve to variable". 
Here is the enum:

```
public enum Voltage
{
    V110, V220, DUAL;
}

```

and here is the class using said enum

```
public class DeskPhone extends Phone
{
    public boolean connected;

    protected DeskPhone(String modelArg, Dimensions dimenstion, Voltage voltage) //enum as parameter
    {
        super(modelArg, dimenstion);
    }

    public void plugIn()
    {
        connected = true;
    }

    public void unPlug()
    {
        connected = false;
    }

    public boolean isConnected()
    {
        return connected;
    }

    @Override
    public String toString()
    {
        if(connected == false)
        {
            return super.toString() + " " + voltage + " not connected"; //results in error
        }

        return super.toString() + " " + voltage + " connected";

    }

```

Why can't I store whatever the constructor is passed within the "voltage" variable and use it in my toString statement?