AddFilter for an AND filter not working properly with my XML

Question

I am following the examples from the Multiple Filters Sample pages to build a page that will filter some data based upon grade levels.
http://indianawea.org/resources/outreachtest.asp
This page is calling the XML file located here:
http://indianawea.org/datasets/resourcesXML.asp
You will notice some weird things right away if you do a simple filter for K-3 Grade Levels. It will find some of the K-3 but not all of them. In addition, when I add another filter (7-8) it doesnt seem to be additive at all but doing an OR filter. The K3 and 7-8 together should only have two results (World Monitoring Day and Survival Guide).
I wonder if it has to do with my XML file struture.The grade levels are stored in a comma delimited string in the database and I pull them out, put them in an array and then loop through the array, creating XML markers for them. This was patterned after the donut example on the Spry page. I am not sure I am doing that correctly because the tags have the same names.
Any help on this is greatly appreciated. And yes, I am working on this on Easter afternoon!
Jon

Answer 1

Thanks for the response Gramps.
http://indianawea.org/datasets/resourcesXML.asp
That is my XML. I have added IDs to the keywordBreakout and gradeLevelBreakout
Looking at this code by Adobe, my XML seems to be in form now with theirs.
http://labs.adobe.com/technologies/spry/data/donuts.xml
In that example they are using there filter to search all toppings if I see that correct, and they have multiple topping nodes with ids. I am trying the same thing. Even with the ID's I am not getting accurate filters.
I have a data field in the database that contains the gradeLevels. It is called gradeLevels in the XML. I thought I would need to parse that out and put them in their own nodes, each grade level at a time, so that the filter can accurate find one when checked. Same for keywords. I could leave them in there comma demlinited list and do a contains instead of an = search with the SPRY filter but I feel that wouldnt be as accurate in case there are keywords that are close in names. I guess I am stumped as to what my next move might be. I'd love some more help gramps!
Jon
NOTE: Even trying this to the gradeLevel node not broken out yields poor results
function ffK3(ds, row, index){ return (row.gradeLevel.match("K-3")) ? row : null; }. It is like it is ignoring certain nodes. The Water Source Book's gradeLevels don't come up in any filter.