Setting shapes background or fill color

Can you tell me how to change the background or fill color of a shape ?

Here is my code, the color is still in blue…

IShapeUIModel vpPageShape = (IShapeUIModel) diagramManager.createDiagramElement(Diagram, vpPage);
vpPageShape.setBackground(Settings.PAGE_COLOR); // DOES NOT WORK
vpPageShape.setForeground(Settings.PAGE_COLOR); // WORKS FOR THE BORDER

I also want to have dotted border line…

Thany you !