Simple Bridge script will not read metadata and triggers Adobe Stock Photos

Question

I have been trying to learn to write scripts for bridge but can't get past the most basic tasks. When I run the script on an open window in bridge it throws an "Uncaught exception metadata" error. The most bizarre thing is it sometimes causes an Adobe Stock Photo script to launch in the extendscript toolkit and throw and the "Uncaught exception metadata" error in that script. My script is as follows:
#target "bridge"
if (BridgeTalk.appName == "bridge")
var items = app.document.visibleThumbnails
for (i=0; i< items.length; i++)
item = items[i]
md=item.metadata
md.namespace = "http://ns.adobe.com/photoshop/1.0/";
Window.alert(md.Title)
Window.alert(i + " "+ " Files Finished")
Basically I was asking to extract the title of each thumbnail from the metadata and show it in a window. I figured if I could do something as basic as that then I could move on and tackle the more complicated tasks that I need to do.
Any ideas of what is going on? Has anyone else accidentally triggered Adobe Stock Photos?

Answer 1

Another bit of info....   As I looked at this further, it seems to be occuring only on those photos where I previously ran camera raw from CS3. I've upgraded to CS5 but have not rerun camera raw since. I understand the camera raw engine in CS3 was different. Could this be involved? Could Lightroom be changing the metadata because the engine is updating the information and I have to save TO file to get this to synch?
update about this camera raw engine possibilty..... it would not appear to be the answer. I have some files that synch even tho lightroom develop says they are using the 2003 process version. I have some files that are on the new version that won't synch.