Use rbf_showInfoMessage in a portal page?

Hi - Is there a way to use rbf_showInfoMessage in a portal page? It seems to work if the HTML included an info message. If there's already an info message up, I can call rbf_showInfoMessage to change it. However, if there is no info message to begin with, then calling rbf_showInfoMessage apparently does nothing. It seems like the HTML structure that the method is expecting is not present on the page. Thanks, Nathan