[Dev-C++] Registry functions

Hello all. I recently looked up usage of registry functions to use the 
Windows registry to automatically start a program. I decided to make 
some test applications to practice using them. This is the code I have 
to get the default value of registry key HKEY_LOCAL_MACHINE:

#include <windows.h>
#include <iostream>

using namespace std;

int main ()
{
 LPDWORD retType;
 LPBYTE retDat;

 RegQueryValueEx (HKEY_LOCAL_MACHINE,
                               "",
                               NULL,
                               retType,
                               retDat,
                               20);
 
cout << retType;
cout << retDat;
 
 return 0;
}

This program compiles fine, but when i run it windows terminates it with 
an error message. If anyone would like to see the error message, i can 
get it. If anyone can possibly come up with an explanation as to why I'm 
coming up with a system error, please help!