Mouse click coordinates

[coonsquad20]

I'm learning Win API and decided to make a tic tac toe game. The game is supposed to check to see if the left mouse button is down and where it is being pressed so it will know when and where to draw the X or O. But the X is drawn in one spot (the only spot I've made code to draw it in) before the mouse is even clicked.

void drawX()
{
	if (WM_LBUTTONDOWN)
	{
             int x = LOWORD(lParam);
	    int y = HIWORD(lParam);
		
             if (x<300 && y<150)
             {
                 //draw X

Why doesn't the computer wait for a response from the mouse before it draws?