JavaScript drop down menu selection

9.7 Build 28765 x64. Bootstrap. Popup window.
I am not sure if there is a bug, but have used old tried and tested code.
Task: quite simply, I want to show the 'date field' if I select 'Schedule date' from a drop down menu.
The code on any selection results in the date field being hidden with no further possible changes upon selection.
I have tried show/hide disabled/enabled and various other configurations of JavaScript <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=24717&image=1&table=forumtopics' class='bbc_emoticon' alt=':blink:' /> , 'I can hide fields' not retrieve data from if statements and I cannot seem to 'process a value from a field' resulting in the if statement not being executed as you would expect - i assume! <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=24717&image=2&table=forumtopics' class='bbcemoticon' alt='<<' />
Is this a bug?
Code:
var ctrl = Runner.getControl(pageid, 'Status'); -- get the status field

if(ctrl.getValue() != 'Schedule date') -- not 'schedule date' (as appears in the drop down menu) then

pageObj.hideField('ScheduleDateField'); --hide the date field!!

ctrl.on('change', function(){

if (this.getValue() == 'Schedule a date'){ -- get a value if schedule date

pageObj.showField('ScheduleDateField'); -- show date selection field so calendar can be entered!!

}

else {

pageObj.hideField('ScheduleDateField'); -- if not hide.

}

});