If you want it to have white background try changing:
code:
<Element xsi:type="FigureElement" Id="FigBkg1">
<Position Top="20" Left="0" Height="15" Width="150"/>
<Figure><Rectangle/></Figure>
<Fill>
<LinearGradient Angle="90">
<Color1><Red>255</Red><Green>255</Green><Blue>255</Blue><Alpha>120</Alpha></Color1>
<Color2><Red>255</Red><Green>255</Green><Blue>255</Blue><Alpha>50</Alpha></Color2>
</LinearGradient>
</Fill>
</Element>