In the UEFA CL the away goal rules is applied after extra time, too. Nordeus implemented it correctly, but I feel for you. Such losses suck.

"For matches played under the knockout system, if the two teams involved in a tie score the same number of goals over the two legs, the team which scores more away goals qualifies for the next stage. If th is procedure does not produce a result, i.e. if both teams score the same number of goals at home and away, two 15-minute periods of extra time are played at the end of the econd leg. If, during extra time, both teams score the same number of goals,away goals count double (i.e. the visiting club qualifies). If no goals are scored during extra time, kicks from the penalty mark (Article 17) determine which club qualifies for the next stage."

source: http://www.uefa.com/MultimediaFiles/...9_DOWNLOAD.pdf