Taxation Law Blunder: My AP LAWCET Mock Test Story

I gave a mock test on Taxation Law yesterday, and I have to admit, it was a disastrous day for me. I scored 48/60, which is quite bad, considering I had studied for this subject well in advance. While going through the answers, I realized I had messed up questions on Tax on Salaries, Capital Gains, and even Double Taxation Avoidance Agreement (DTAA). I remember thinking, "Meh, I know DTAA so I'll get this question right," only to find out I had marked the opposite. My weak area was, as always, Tax on Salaries. I got only two questions right out of five. I guess I need to study more cases on this topic. Has anyone else struggled with Taxation Law?