For instance in this post:
http://forums.creativecow.net/readpost/191/857043
You gave a url of a page that had working data sets in them and I could see what you were actually trying to do. Though this is gone now I could see the xml file you were working with and the way you were using DW to use the xml content to build your page. Your newest url doesn't have any xml file associated with it. Though it does give me a basic layout of what you want to do I would really like to see the xml file you are working with to give me something to work with.
It sounds like you have multiple xmls (data sets) that you want to switch between so I'd like to know the location of these files please. I don't work with data sets much so your files will be helpful for me to answer your question.
Abraham
