Show/Hide Sub Forms in LiveCycle ES 8.2

Hello All,

I am using Livecycle to create a form and want following functionality:

If a particular value is selected from drop-down box, it should hide/show a sub-form.

However, I am not able to do it. I looked at adobe livecycle docs, Adobe user forums, and GOOGLE...but fail to run the code.
 
I have used following PDF as reference:
http://partners.adobe.com/public/developer/en/livecycle/designer/pdfs/ChangingObjectPresence.pdf
 
This code below is written on drop-down box and I have BMD_Form as subform

----- form1.POS.Emphasis_info.subformOptions::change - (JavaScript, client) ------------------------
switch (xfa.event.newText) {
case "Invisible":
form1.POS.BMD_Form.presence = "invisible"; or
break;
case 'Hidden':
form1.POS.BMD_Form.presence = "hidden";
break;
default:
form1.POS.BMD_Form.presence = "visible";
break;
}

Thanks
Viral