New Post: the operation GetGroupCollectionFromUser doesn't work for some users

I have found that the $().SPServices.SPGetCurrentUser() returns an empty logonName when used at a subsite level, versus a root site level, where the LogonName does populate properly. I am using SPServices 0.7.2 and Win 7 with MOSS 3.0/SP 2007. I had to resort to placing a div with LogonUser and then hiding with styling and then pulling .html() from the Div, in a separate CEWP, then passing that into a variable and using that variable versus the direct call($().SPServices.SPGetCurrentUser()), in order to use the GetGroupCollectionFromUser for a sub site.