Dynamic Window - SetMandatory - can't undo Mandatory field

I have this in my calculation field, where MyAttribute is a boolean value displaying as a checkbox in the Web form.

import System

static def GetAttributeValue(Request):

MyValue = false

if Request._MyAttribute == true:

MyValue = true

return String.Format(":SetMandatory(_TargetField, {0});", MyValue)

I have also tried this:

import System

static def GetAttributeValue(Request):

MyValue = false

if Request._MyAttribute != null and Request._MyAttribute == true:

MyValue = true 

return String.Format(":SetMandatory(_TargetField, {0});", MyValue)





Both seem to work fine as far as setting the target field as mandatory.  The issue is that when MyAttribute is de-selected, the field does not go back to non-Mandatory.



Is there any trick to make this work?

Thanks!