Windows Phone Silverlight 8.1 Unit Test Exception

Today I start implementing unit tests for my WP 8.1 Silvelight app, and on start I found a problem.

I have async static method wchich has try / catch block and here it is.

Some code before explanation: Method to test (not 100% real code but have same logic):

async public static Task<string> MyMethodAsync(string param, string param2)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://url.pl");
    request.Method = "GET";
    string result = string.Empty;

    try
    {
          response = await request.GetResponseAsync(); 
    }
    catch(Exception e)
    {
          result = "error";
          return result;
    }

    result = "Expected result value";
    return result;    
}

And now I want test it in unit tests:

[TestMethod]
public void TestMethod()
{
    string result = StaticClass.MyMethodAsync("param1", "param2").Result;

    Assert.IsTrue(result == "Expected result value");
}

Problem is that test method hangs or return fail everytime, even if in app method returns expected values every single time.

It seems to "catch" internal exception before try / catch in MyMethodAsync and raise fail event.

Do you have any idea what's wrong?