Wanted to bump this topic.. I'm running into a similar issue.
Below is my code. Works perfectly fine when added to the newform.aspx page of my list. But when I dropped a (new item) Dataview WebPart onto a custom aspx page in SPD and added the same code to a content editor, it doesn't work! Is there an explanation or fix for this? I have a requirement to add this form to a separate page on the SharePoint site but don't want to go the InfoPath route if I don't need to.
$(document).ready(function(){ $().SPServices.SPCascadeDropdowns({ relationshipList: "KPIs", relationshipListParentColumn:"Program", relationshipListChildColumn:"KPI", parentColumn:"Program", childColumn:"KPI" }); });