Can't trap mouse WM_LBUTTONUP events

I have a running application in x64 mode and I wanted to trap a WM_LEFTBUTTONDOWN event, translate the mouse position to my real world coordinates and write out those coordinates on my GUI and then immediately pick up the WM_LBUTTONUP event and basicall erase the text I had just written. Either I'm not getting the second event or my XOR mode of writing is not working. Any ideas? Here is the code:

!======================================
      case (WM_LBUTTONDOWN)
!======================================
         mx = LOWORD(lParam)       
         my = HIWORD(lParam)
!        mx = GET_X_LPARAM(lParam)
!        my = GET_Y_LPARAM(lParam)
         Call M2R (mx, my, xm, ym)
         write(TxtOut,'(f8.2,1x,f8.2)') xm, ym
         hDC = GetDC(ghWndMain)
         if (hDC == NULL) Then
            WinMainProc = 0
            return
         end if
         ghPen = CreatePen(PS_SOLID, 2, RGB(0,0,0))   ! Thick black Pen
         bret = SelectObject(hDC, ghPen)
         ret = SetROP2(hDC, R2_XORPEN)
         iret = SetBkMode(hDC,TRANSPARENT)
         bret = textOut(hDC, mx, my, TxtOut, 17)
         WinMainProc = -1
         return

!======================================
      case (WM_LBUTTONUP)
!======================================

         bret = textOut(hDC, mx, my, TxtOut, 17)
         bret = DeleteObject(ghPen)
         bret = DeleteDC (hDC)
         WinMainProc = -1
         return

Thanks for looking at it. BTW, the first part is working flawlessly. Just not erasing the text I've written.

Brooks