Unable to use WinAPI functions in CLR project

[LeadDeveloper]

Hello!
I am working on a Windows Forms application using CLR. Up to now, everything has gone great, but I am trying to set a pixel in the form with the standard SetPixel() method supplied by the Windows API.
Unfortunately, whenever I try to do this, I get Error LNK2019, saying essentially that the SetPixel() function is an 'unresolved external symbol.'
This is a huge problem for me because without being able to set pixels I will not be able to even get started on the actual rendering I'm planning to do with the application.
(I'm using SetPixel() as a way of making a temporary 'graphics engine' that can draw on windows. I've made one before that worked fine (albeit painstakingly slowly), so I know I'm doing everything else perfectly. Obviously, when I start to use real graphics and rendering in my application, I'm not going to use SetPixel() but I want to be certain that Windows API functions still work, as they will be the backbone of my engine.)



Code:
(in RenderBase.h)
#ifndef RENDERBASE_H
#define RENDERBASE_H

#include <Windows.h>
class RenderBase
{
public:
void SetPixel(int x, int y, COLORREF color);
COLORREF GetPixel(int x, int y);
};

#endif


(in RenderBase.cpp)
#include "RenderBase.h"
void RenderBase::SetPixel(int _X, int _Y, COLORREF _Color)
{
HDC hDC = GetDC(GetActiveWindow());
::SetPixel(hDC, 12 + _X, 37 + _Y, _Color); //Offset the coordinates given so they show where I want them to
}

COLORREF RenderBase::GetPixel(int _X, int _Y)
{
HDC hDC = GetDC(GetActiveWindow());
return(::GetPixel(hDC, 12 + _X, 37 + _Y));
}


____
(Sorry for the bad formatting, I couldn't figure out how to get the normal code thingy working, so I had to copy it normally.)


Thank you in advance for your help!

[Thomas1965]

Didi you include Gdi32.lib ?

[LeadDeveloper]

Just tried including it, and it still doesn't compile. Still getting Error LNK2019 and the Form Designer doesn't open properly anymore.

[Thomas1965]

Can you post the code of the form?

BTW. Why do you want to use the Windows GDI functions instead of the Graphics class?