PROGRAMMING THE FMC FAILED TO MAKE CROSSING RESTRICTION.

Narrative

CLRED OUT OF FL260 'CROSS SCY AT FL220; GLADD AT 11000'.' CAPT FLYING; I SET ALT SELECTOR/ALERTER ON 11000'. FMC SET FOR RESTRICTION SCY AT 220; GLADD AND 250 KT; 11000'. CAPT TOOK MCP OUT OF VNAV INTO LEVEL CHANGE. DSNDING OUT OF 21700' APPROX 10-15 DME BEFORE SCY; CENTER STATED 'CROSS SCY AT FL220.' I ALERTED CAPT TO ALT BUST; DSCNT STOPPED AT 21500'; HE CLBED BACK TO FL220; MAINTAINED UNTIL SCY VOR. REMAINDER OF FLT UNEVENTFUL. DON'T KNOW IF CENTER SAW US GOING THROUGH FL220 OR JUST A FRIENDLY REMINDER. FMC IS SMART; BREEDS COMPLACENCY -- PROBABLY TAKES AS MUCH ATTN MONITORING FMC AS DOES IF YOU JUST FLY IT YOURSELF. WOULD NOT HAVE OCCURRED IF 1) EITHER OF US HAD WATCHED MORE CLOSELY; 2) VNAV LEFT ENGAGED 3) ALT SELECTOR/MCP SET AT FL220 INSTEAD OF 11000'. CONTRIBUTING FACTOR; SHORT LEG; AMOUNT OF WORK SAME AS LONGER LEG; TIME COMPRESSED; LESS TIME TO MONITOR PLT FLYING. SUPPLEMENTAL INFO FROM ACN 87367. I FAILED TO SELECT THE MODE CONTROL PANEL ALT WINDOW BACK TO FL220 INSTEAD OF 11000'.