Marketing question | Marketing homework help

You are the marketing communications director for a new brand of energy drink, and you have just run a communications campaign to launch the new product. The CEO tells you that she will be using sales or sales-based metrics, such as return on investment (ROI) or lifetime value of the customer, as the only measure for assessing the effectiveness of the communications campaign. How do you argue that a sales-only approach is not appropriate?  Explain your approach in no less than 250 words.