Initial View is disabled on a Form created in LiveCycle ES2

Hi,

I am trying to change the preferences using the Initial View tool in Acrobat.  I want to set it to open with bookmarks visible.  However, the entire initial view page is disabled for me.  The PDF is one that I created myself using LiveCycle Designer ES2.  I am using Acrobat Pro X.  Why would this functionality be disabled?

Thanks,

Nicole