required = "false"; Not working JavaScript

Hello,

In my document I have groups of radio buttons and depending on selections depends on whether text fields are shown visible and required.

Inside the buttons I run individual scripts, the only real difference between them are the actions taken if the conditions are met;
--within the CustomValue button--
var fldValue = this.getField("ItemValues").value;
if (fldValue == "CustomValue"){
 this.getField("ValueTxt").display = display.visible;
 this.getField("WeightTxt").display = display.visible;
 this.getField("ValueTxt").required = "true";
 this.getField("WeightTxt").required = "true";
}
^ this part works fine.
--within any other button--
var fldValue = this.getField("ItemValues").value;
if (fldValue !== "CustomValue"){
 this.getField("ValueTxt").display = display.hidden;
 this.getField("WeightTxt").display = display.hidden;
 this.getField("ValueTxt").required = "false";
 this.getField("WeightTxt").required = "false";
}
^ this part sets the fields to hidden no problem, it does not however set the field to not required.
I have also commented out the hidden scrips to see if it was simply because the button was hidden but it still remains required.
As a half measure I have set the border colour to turn red then black instead of required and not but for full functionality I would like them to be required and not. I don't quite know why it is not functioning properly as 'usually' this method works for me.

As always any help is appreciated
Thank you in advance

Alex Horsfield