Sometimes you have to label a diagram in the listening test. For example, the diagram below comes from Cambridge IELTS book 7.
Many students miss the answers for this type of question because they get "lost" on the diagram. They don't know where to look.
There is one simple technique to avoid this problem: whenever you see a diagram, look for the question numbers. You will always hear the answers in the correct order, so your eyes should go to the first question number first, then move around the diagram following the numbers.
For the question above, your eyes should be looking at the bottom of the picture (question 11) when the recording starts, and your ears should be listening for "stop B".