exigent pickiong problem

OpenGL OpenGL: Basic Coding
1

I want to pick some points in my projection. In GL_RENDER, I can draw the scene correctly, but in GL_SELECT, if I comment out glRenderMode(GL_SELECT) , then it will be drew in not the correct place, far away from the correct place, and will become smaller. Codes as follows:

void CProjectView::SelectPoints(CPoint point)
{
GLint viewport[4];
int x,y;

x=point.x;
y=point.y;
glGetIntegerv(GL_VIEWPORT,viewport);

glSelectBuffer(BUFSIZE,selectBuf);
glRenderMode(GL_SELECT);

glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();

gluPickMatrix(x,(viewport[3]- y),500.0,500.0,viewport);
gluPerspective(10*ZoomFactor,aspect,1,10000.0);

DrawProcessedPoints(GL_SELECT);

glSelectHits=glRenderMode(GL_RENDER);

glMatrixMode(GL_PROJECTION);
glPopMatrix();

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void CProjectView: rawProcessedPoints(GLenum mode)
{
glMatrixMode(GL_MODELVIEW);
glPushMatrix();

glInitNames();
glPushName(0);

glTranslated(SYSVIEWX, SYSVIEWY, SYSVIEWZ);	
glRotatef(viewAngle_Z, 0.0, 0.0, 1.0);
glRotatef(viewAngle_Y, 0.0, 1.0, 0.0);

for(int i=0;i<nProDataLength/6;i++)
	{    if(mode==GL_SELECT)
	     glLoadName(i+1);
     glPointSize(2.0);
     glBegin(GL_POINTS);
	   glVertex3f((float)(pProcess[i*6]-pProcess[0]),
		   (float)(pProcess[i*6+1]-pProcess[1]),
		   (float)(pProcess[i*6+2]-pProcess[2]));
	  glEnd();		 
	}

glPopMatrix();
}
void CProjectView::OnSize(UINT nType, int cx, int cy)
{
CView::OnSize(nType, cx, cy);
CSize size(cx,cy);
aspect = (cy == 0) ? (double)size.cx : (double)size.cx/(double)size.cy;
glViewport(0,0,cx,cy);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(10*ZoomFactor,aspect,1,10000.0);

gluLookAt(eyePosition.x, eyePosition.y, eyePosition.z, lookPosition.x, lookPosition.y,
		  lookPosition.z, upAxis.x, upAxis.y, upAxis.z);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glDrawBuffer(GL_BACK);
glEnable(GL_DEPTH_TEST);
InvalidateRect(NULL,FALSE);

}