variable unassigned

Question

I have created a very simple little program that adds a value to a string variable once tested if its empty.... My problem is that VS 2010 tells me that the variable is uns=assigned in my if conditional parameters. I have done java and c++ for a number of months now with little trouble so this is boggling me...

Here is my code:

 static void Main(string[] args)
        {
            string anotherStr;

            if (anotherStr == "") 
            {
                anotherStr = "bye";
            }

            Console.ReadKey();

        }

 
I appreciate the help