Picking an object / Object selection

I am trying to implement object selection using gluPickMatrix(). I am developing my program using SDI application in .NET. OpenGL is drawn in CView. I have a problem of getting viewport value glGetIntegerv(GL_VIEWPORT,viewport). It does not return valid value. I skipped the above problem when using gluPickMatrix with the value of CView width and height gluPickMatrix((double)x,(double)(WindowCView.viewport[3]-y),5.0,5.0f,WindowCView.viewport); However, the hits returned (hits=glRenderMode(GL_RENDER)) is always zero. I have followed the steps described in the redbook. Any idea is really appreciated. Many thx in advanced