Using branching to ask different questions to males and females

In the midst of a larger survey I have a 25 item questionnaire with different items for males and females. The male and female items are in separate blocks. I have assumed that the way to do this is to use branching and to show the male block only to males and the female block only to females. However, I have not gotten this to work as intended. (In Preview all questions are being shown to me regardless of whether I indicate I am female or male.) Here's what I tried: In "Survey Flow," I have my various blocks. I went to the question block intended for males. I clicked "Add below" and indicated that I wanted to add a branch. I then added a condition such that the branch would be triggered if the question "What sex are you?" was answered "Male." Clicked "OK." Did the same for the female items. What am I doing wrong?