Topic: linkurl not working

I am using  tiltviewer pro 1.3.1 and and nextgen 1.5.3

Each time I put in the code on the wordpress site

<p style="text-align: center;">[tiltviewer id="17" width="800" height="800" linkurl=""] </p>
I have the Show Link Button: set to true.
Yet the flipside of the image still does not come up with a button. 

Any suggestions?