jpGraph - cannot change line colour (or color)

Using jpGraph, an excellent package for plotting graphs from database data via PHP, I hit a problem: setting
$lineplot->Setcolor("blue"); 
had no result. Nor did
$lineplot->SetWeight(2);
Eventually, I sent off an enquiry to jpGraph - and back came a very prompt reply (from the Far East):

in version 3.5.0b1, methods to change designs of each plot should be used after $graph->add($plot) method.

This is really counter-intuitive. But it works.

So it goes like this

$bplot = new BarPlot($data1y);
$graph->Add($bplot);
 
// NOW change properties of the plot - these work ONLY after calling Add()
$bplot->SetWeight(0);
$bplot->SetFillGradient('#FFAAAA:0.7', '#FFAAAA:1.2', GRAD_VER);    
 

There is a note in the documentation included as part of the package, at:

jpgraph-3.5.0b1/docs/chunkhtml/ch29s02.html