Did you load a video that contains sound?

There really is not enough information in the question you asked to give you a reasonable answer. I am assuming you have Movie Edit Pro 17.

When you load a video that contains sound, it will load both the visual and audio parts. the audio piece will be directly below the visual part. In some cases you may have video which has the audio as a separate file... though I have not seen this before with any cameras I have used... I have heard this is a case.

In that case you have to load in the audio separately, and then align the audio and visual parts.