BE58 PLT FAILS TO MEET ALT RESTR ON TEB SID FROM TEB.

Narrative

I WAS CLRED TO DEPART TEB ARPT VIA THE TEB 5 DEP. THIS DEP PROC CALLS FOR MAINTAINING AN ALT OF 1500 FT MSL UNTIL 4.5 MILES FROM THE ARPT; THEN CLB TO 2000 FT MSL. PRIOR TO TAKING THE RWY; I CAREFULLY REVIEWED THE DEP PROC WITH MY DAUGHTER (A STUDENT PLT) AND SET THE ALT SELECTOR ON THE AUTOPLT TO 1500 FT. AFTER ROTATION AND GEAR-UP (PASSING THROUGH 500 FT MSL) I ACTIVATED THE AUTOPLT AND SET MY VERTICAL SPEED TO A CLB RATE OF 1000 FT PER MIN; BUT I FAILED TO 'ARM' THE AUTOPLT SO IT WOULD 'CAPTURE' THE ALT AND LEVEL OFF AT 1500 FT MSL. APCHING 1400 FT MSL; I CONFIRMED THE AUTOPLT SETTING OF 1500 FT AND THEN FOCUSED ON MY TURN TO THE NEXT HEADING. AT 1700 FT MSL THE ALT ALERT SOUNDED AND I REALIZED THE AUTOPLT HAD FAILED TO CAPTURE THE PROGRAMMED ALT; SO I CHKED THE DME TO DETERMINE IF I HAD FLOWN 4.5 MILES FROM THE ARPT AND WAS PERMITTED TO CLB TO 2000 FT MSL. I WAS ONLY 3.3 MILES FROM THE ARPT. I DISCONNECTED THE AUTOPLT AND PUSHED THE YOKE FORWARD TO BEGIN THE DESCENT BACK TO 1500 FT MSL. AT THAT MOMENT THE DEP CTLR RADIOED ASKING IF I WAS AT 2000 FT MSL. I REPLIED YES. I HAD ALREADY BEGUN A DESCENT BACK TO 1500 FT. THE REMAINDER OF THE FLT WAS WITHOUT INCIDENT.