On Select Event Doesn't Always Cause Scripted Behavior

I have a Dropdown box, in which I've scripted a Datasource Load in the On Select event.  The script is as follows:

var section = DROPDOWN_SECTION.getSelectedText();

APPLICATION.createInfoMessage(section);

if(section != "")

{

  APPLICATION.createInfoMessage("Here");

  DS_REPORT.loadDataSource();

  DS_REPORT.setVariableValueExt("psEnter Section ", section);

  DROPDOWN_REPORT.setItems(DS_REPORT.getMemberList("_WpnEIGznEeWMV6Xw3BhiaA", MemberPresentation.EXTERNAL_KEY, MemberDisplay.TEXT, 100, "Select Report"));

}

You can see that I've scripted it such that, if a value is selected from the list, a Datasource is loaded, with the selected value being passed to a parameter in order to limit the returned results.

You can see that I have two info messages.  Every time I select a new Dropdown value, these messages are displaying as I would expect.  However, sometimes when I select a new value, the Datasource load doesn't occur.  I'm wondering if I might be missing something that can ensure that the load gets fired.  Or perhaps there's a better way to script this.