If this is the first imported media, iAnalyse loads it into the timeline and the audio player. You also can use it on temporal representations.
You can increase the size of the window if you want to increase the frequency precision. You can decrease the step parameter to compensate the temporal imprecision. By decreasing the size of the window, you increase the temporal precision but you decrease the frequency precision.
Decrease the dynamics threshold if the amplitude of the audio file is lower. However, by default, the file is normalized before the FFT computation. You can disable this normalization in the preferences.