Autopilot

[Pigwiggen]

What am I failing to do when, having preset my planned altitude, heading, climb speed, and then following climbout, I click on the autopilot button in my aircraft and then sit back to watch it go streaking straight through that altitude and at a speed far in excess of the one I'd set up.
Help, folks.
Thank you.
So far I've tried it with the Cessna and Airbus 321.

[paiken]

Just turning on the autopilot might not do everything you are expecting. You also need to press the buttons for ALT, NAV/HDG, and on units so equiped, the SPEED buttons. They should light up when active. If you are doing all of that and still having problems, then I'm not really sure what the issue could be.

[Pigwiggen]

Thanks for that. I'll check that little lot is done.

[falcon409]

Also, in combination with the "Speed" button there should be one labeled "AT" (Autothrottle) that will also have to be pressed otherwise it will not recognize the speed setting. Another thing to remember, when landing, if you simply click the "AP" button to turn off the autopilot, you will also have to press the "AT" button again as that normally stays active even after the "AP" button is pressed and you'll be left wondering why you can't slow down.