Many shows are produced by media firms who also publish magazines. Too often an in-house magazine sponsors the show but does not provide any value-added benefit:
The publisher/ad sales staff do not help in selling booth space.
The editorial staff refuse to promote the show in the editorial pages.
In fact, in many cases the two remain completely separate "silos" and reap no benefit from the common ownership. That is because magazine people are from Mars and trade show people are from Venus.
The overall suggestion is to create a common understanding and, better yet, a common incentive to producing a successful show. For example, there could be a profit distribution to the show and the magazine.
For more on this subject, see the white paper "Optimizing the Magazine/Trade Show Relationship" (written by Michael Hough in 1999). To access this paper, go to www.americanbusinessmedia.com, click on Resources and then White Papers.