Complete at least 2 goals in a sam challange
there are only 2 challenges and I need 4 and I've already done 2/4 EA Give me back my tix
Ideas
If you play the missions, more slam mission will appear as you unlock and level. It's not a game issue, it's a skill issue. I did the 4 just fine! Also, you need to solo them, so that you complete all the achievements yourself. Or party with someone that hasn't done all the slams and that other person needs to be party leader as well. Good luck