Need help and comments on Rank 1-> 2 test

I just failed the test and I dont know why. Do I have to kill certain amount of enemies in that time limit? Did I do something wrong? At the start of the test,I ran around the pillars to find the hiding enemies. At some point I even climb up the pillar. Soon after. Wave 1 was cleared. But they say that the mission failed. (T_T ) helppp~