Error in Qt: undefined reference to `_imp__GetPixel@12'

When I use the function: GetPixel, I get an error: undefined reference to `_imp__GetPixel@12'

#include 
#include 

inline int getcolor(int x, int y, HWND hwnd=0) {
    HDC hdc =(hwnd ==0) ? GetDC(st->getHWND()) : GetDC(hwnd);
    int color = GetPixel(hdc, x, y); //error, Not compiled
    return color;                        
}