CRJ200 FLT CREW MISSED THE CROSSING RESTRICTION ISSUED ON DESCENT.

Narrative

I WAS OPERATING AS PNF INTO ATLANTA. DURING ARR; WE RECEIVED A XING RESTR 75 NM N OF RMG VOR AT FL280 TO CROSS 40 NM N OF RMG AT FL240. THE XING RESTR WAS PROMPTLY LOADING INTO THE FMS AND ALT SET IN THE ALT WINDOW. I THEN PROCEEDED WITH PNF DUTIES OF PREPARING FOR APCH INTO ATLANTA BY OBTAINING LCL WX AND SETTING LNDG DATA. SHORTLY THEREAFTER; WE WERE QUERIED BY ATC ABOUT MEETING OUR RESTR. IT WAS ONLY THEN THAT I NOTICED WE HAD OVERFLOWN OUR DSCNT RESTR AND WOULD NOT BE ABLE TO COMPLY. ATC THEN ISSUED AN AMENDED DSCNT TO FL270. LATER; IN DISCUSSION WITH THE CAPT; I FOUND OUT THAT HE WAS UNDER THE IMPRESSION DURING THAT TIME THAT IT WAS MY LEG. AS A RESULT; HE SUBSEQUENTLY WAS EXPECTING ME TO COMPLY WITH THE ISSUED XING RESTR. MY FAILURE TO ENSURE THAT HE BEGAN THE DSCNT AT THE APPROPRIATE TIME WAS ALSO A CONTRIBUTING FACTOR. IN ORDER TO PREVENT THE RECURRENCE OF THIS EVENT; I WOULD MAINTAIN EXTRA VIGILANCE WHEN ISSUED XING RESTRS AND POSSIBLY DELAY ACCOMPLISHING CERTAIN PNF DUTIES UNTIL A DSCNT TO MEET A RESTR HAS BEEN INITIATED. FURTHERMORE; PROPER WORKLOAD MGMNT IS IMPORTANT IN MAINTAINING SITUATIONAL AWARENESS DURING BUSY PHASES OF FLT.