I am able to get the green lights fir the localizer but when I get about 10 or 15 miles out and got to glideslope on ap and the the fd the plane starts to climb For example atc tells you to go down to 1500 ft runway 4l and now you are on the localizer its green on the cockpit you are on autpilot. Atc says you are clear to and and you click on the glideslope both on the autopilot and the fd and craft stats to go up and up.

please helpme and tell me what I am doing wrong, have not had problems woth 737 md-80 or 767 what am I doing wrong ? need some good advise.  thansk Ronny