ThinkPad 52: No LCD+CRT in parallel

Hi, out there, I've been trying, without success, to get my computer display (LCD) and an external monitor (CRT, respectively beamer) working in parallel under Suse Linux 9.3. My box is an IBM (Lenovo?) thinkPad R52 Modell 1860-5EG (well, comparatively low cost). Pressing the FN+F7 keys always results in: either LCD on and CRT (beamer) off or LCD off and beamer on (in the right solution) Does anybody have a clue how to get parallel operation? Thanks for all hints, Walter