call property of a subclase using referenc of baseclase

[dududada]

Hi there,
both ways works without any error, but only this way shows the property value: Console.WriteLine("wight: " + ((Porsche)A).wight);
and this with ',' instead of '+' does not:
Console.WriteLine("wight: ", ((Porsche)A).wight);
I made a C# console app with VS.NET 2012.
It has three clases.
Class Auto is the base class.
Class Porsche the subclase.
So, within those program part of this console app, I just have like to see some proofs, about changing of objectreferences.
Only Porsche has a property 'wight', it will set by construktor.
Then there is a class called AnyObject, which has just one method and this method excpect a 'Auto' type reference.
The methode will make a proof what type is it, and if it is Porsche then there shall be written 'wight = 10'.
But this happend only if I put it like that:
Console.WriteLine("wight: " + ((Porsche)A).wight);

So if I take look to those writeline methode, what its excpect while using ',' then there is "object arg0".
Why is it loosing the value of the property?

here the whole code:

[COLOR=Green]// Base clase Auto [/COLOR]
 public class Auto 
 {              }

// derivade clase Porsche

public class Porsche: Auto 
    {         
      public int wight { get; set; } 
         
      public Porsche()[COLOR=Green] //Construktor [/COLOR]
        { this.wight = 10; } 
    }

// this clase just take any reference of Auto types

public class AnyObject 
 {  
       public void anyTask(Auto A)
        {     
            if (A != null)
           { 
                if (A is Auto)
              {  
                 Console.WriteLine("wight: " + ((Porsche)A).wight); 
                 }
                 else
                      Console.WriteLine("unknown type."); 
         }
    } 
}

// here we have program part of this app, where the class AnyObject is used

 class Program   
  {  
       static void Main(string[] args)
        {            
             Porsche p = new Porsche();             
             Auto a = p;
             [COLOR=Green] // base clase gets  a referenc of a subclase[/COLOR]
            AnyObject myOb = new AnyObject(); 
            myOb.anyTask(p);              
           Console.ReadLine(); 
        }
 }