Error inconsistent accessibility method C#

namespace BanjoStore
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a Banjo!
            var myFirstBanjo = new Banjo("it's my first!", 4, 67, Banjo.BanjoState.Used);
            //Oh no! The above line didn't work because I can't access BanjoState!
            //I can't used the enum to pass in the value because it's private to the 
            //Banjo class. THAT is why the error was visible in the constructor. 
            //Visual Studio knew this would happen!
        }
    }

    class Banjo
    {
        //These are private by default since there isn't a keyword specified 
        //and they're inside a class:
        string description;
        int price;

        //This is also private, with the access typed in front so I don't forget:
        private int banjoID; 

        //This enum is private, but it SHOULD be:
        //public enum BanjoState
        //Even better, it can be internal if only used in this assembly
        enum BanjoState
        {
            Used,
            New
        }

        public Banjo(string inDescription, int inPrice, int inBanjoID,
                     BanjoState inState)
        {
            description = inDescription;
            price = inPrice;
            banjoID = inBanjoID;
            BanjoState state = inState;
        }
    }
}

class BanjoState //This class is internal, not public!
{
    // Methods, properties, fields, events, delegates 
    // and nested classes go here.
}

public class Composite
{
    ...

private Composite buildComposite(ComboBox subs, ComboBox bas)
{
    ....

internal class A{}

public class B
{
    public B(A a){}
}

//Make this public
public class A{}

public class B
{
    public B(A a){}
}

internal class A{}

//Make this internal
internal class B
{
    public B(A a){}
}

internal class A{}

public class B
{
    //Make only the constructor internal
    internal B(A a){}
}

using (SqlConnection con = ArxeiaConnection.getARXEIAStringConnection(config.Tenant + "_" + config.Database))
{
    using (SqlCommand cmd = new SqlCommand(query, con))
    {

using (SqlConnection con = ArxeiaConnection.getARXEIAStringConnection(config.Tenant + "_" + config.Database))
using (SqlCommand cmd = new SqlCommand(query, con))
{