Stroke align inside / Stroke width

I'm not sure where I'm going wrong here, the internet and these forums say to script a change of Stroke to be INSIDE (which I'm after) is the following:

myRectangle.strokeAlignment = StrokeAlignment.INSIDE_ALIGNMENT;

But I just get an error "StrokeAlignment is undefined"

If I try it as:

myRectangle.strokeAlignment = INSIDE_ALIGNMENT;

I get the same "INSIDE_ALIGNMENT is undefined".

My full bit of code drawing a box and just trying to make the stroke inside:

var myRectangle = idoc.pathItems.rectangle(r[1], r[0], r[2]-r[0], r[1]-r[3]); // dimensions set earlier in the script
myRectangle.name = "Banner Border";  
var swatchToUse = app.activeDocument.swatches["BannerBorder"]; // swatch made earlier
myRectangle.strokeWidth = 88; // not working either, pt size always comes out as 1, regardless of this setting         
myRectangle.fillColor = NoColor;
myRectangle.strokeColor  = swatchToUse.color; 
myRectangle.strokeAlignment = StrokeAlignment.INSIDE_ALIGNMENT; // errors

Can someone point me in the right direction to get the stroke alignment to be INSIDE, as I'm just going round in circles with google/forum results!

Thanks in advance!