Filter basics..

[A.Brady]

I'm having some basic trouble getting an XML filtered through a DataSet from an XML Component.
I've rummage through several posts and decided that I'm missing some basic knowledge :

I've dropped the function code onto the main screen:

this.myDataSet_ds.filtered = true;
this.myDataSet_ds.filterFunc = function(itembject) {
// filter out record cdafr22d
return(item.count != "cdafr22d");

The XML data is pretty straight forward:

<file name="DFID">
<count>cdafr22d</count>
<file>flash/PDFs/cdafr22d.pdf</file>
<image>flash/images/cdafr22d.jpg</image>
<description>OTHER GLOBAL ISSUES</description></file>

<file name="Guatemala ">
<count>cdafr22h</count>
<file>flash/PDFs/cdafr22h.pdf</file>
<image>flash/images/cdafr22h.jpg</image>
<description>OTHER GLOBAL ISSUES</description></file>

I've set up the data trigger from a simple button to a data grid, a la the Component Wizard, and that all works, but no filter.
Simple, or simply not possible?
-A