glGenTextures causes GL_INVALID_OPERATION

I noticed that glGenTextures isn't generating textures and instead causing GL_INVALID_OPERATION error in the project I'm currently working on, first I thought that there is a missing glEnd or something, I looked for such a thing but everything was OK, so I created this program:

Code:

---

#include <windows.h>
#include <gl/gl.h>
#include <gl/glu.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow) {
        UINT texture = 0;
        glGenTextures(1, &texture);
        GLenum e = glGetError();
        switch (e) {
                case GL_NO_ERROR:
                        MessageBox(NULL, "GL_NO_ERROR", "", MB_OK);
                        break;
                case GL_INVALID_VALUE:
                        MessageBox(NULL, "GL_INVALID_VALUE", "", MB_OK);
                        break;
                case GL_INVALID_OPERATION:
                        MessageBox(NULL, "GL_INVALID_OPERATION", "", MB_OK);
                        break;
        };
        return 0;
}

---

and it gave the same error :confused:
I loaded one of my previous projects and it worked OK.
So what am I doing wrong? does glGenTextures require some initialization (MSDN says nothing about this)?

because you have not setup a rendering context and initialized OpenGL.

well, I guess this is the reason, I was testing a texture class I made to simplify texture operations, and I tried to test it in WinMain, thanks for the response :)