You've probably already worked it out by now, but in case you're still having this problem open the render view window, from the top menu bar choose render - render and you'll get up the options for which camera to render through in terms of top, side, perspective, front and other cameras you have in the scene. Current will tell you the camera that is currently in use, which in your case would say perspective so simply select the camera you want to use and Maya will render this one instead.

Changing your panel view to the camera will not change the camera that's being rendered, so the way to move between different cameras would be through this rendering menu in the render view window.

Hope that helps.