How to add a graphics script but using a variable vs a hard coded value

[#1]

I'm trying to have a dynamic drawing of a spec "box" in graph builder but I can't seem to get it to work.  I've tried making the usl and lsl expr(usl) and expr(lsl) and done eval(eval expr()) but that did not work either.  Any suggestions would be greatly appreciated!

rpt=dt<<Graph Builder(
	Size( 527, 456 ),
	Show Control Panel( 0 ),
	Graph Spacing( 5 ),
	Variables( X( :Min ), Y( :Max ) ),
	Elements(
		Points( X, Y, Legend( 3 ) ),
		Ellipse( X, Y, Legend( 5 ), Coverage( "99%" ), Mean Point( 1 ) )
	),
	SendToReport(
		Dispatch( {}, "Graph Builder", FrameBox,
			{Add Graphics Script(
				2,
				Description( "" ),
				Pen Color( "red" );
				Line( [lsl, usl], [usl, usl] );
				Line( [usl, usl], [lsl, usl] );
				Line( [lsl, usl], [lsl, lsl] );
				Line( [lsl, lsl], [lsl, usl] );
			)}
		)
	)
);

Want it to look like this (this was using the hard coding instead of lsl and usl)