mdbg can't debug my hello world program

In order to try out mdbg, I have the following simple hello world program:

// kkk.cs
using System;

class HelloMain
{
    static public void Main()
    {
        Console.WriteLine("Hello");
    }
}

Compile it with csc /debug kkk.cs, this yields:

kkk.exe
kkk.pdb

I then do (from the visual studio command line):

mdbg kkk.exe

or

mdbg !r kkk.exe

I got:

Error: The request is not supported. (Exception from HRESULT: 0x80070032)

I know this question is super old, but I just ran into this and found the 'fix' for this problem. Adding here for any other Googlers..

I have two directories:

• C:\Program Files\Microsoft SDKs\Windows\v7.1\Bin\NETFX 4.0 Tools\Mdbg.exe
• C:\Program Files\Microsoft SDKs\Windows\v7.1\Bin\NETFX 4.0 Tools\x64\Mdbg.exe

Make sure you're launching the correct version (in my case, the x64 version) and doing a 'Run as Administrator' when opening the command prompt.