Controlling slider with keyboard

Before you leave this topic, I would like to use slider in Builder, but have the marker default to a particular value (like ‘marker start’ in the old Rating scale). From Pablo’s example I thought I could proceed the slider with a code segment like:
mySlider.markerPos = 6 #in Begin Routine
or
mySlider.markerPos = 6 #in Begin Routine
mySilder.draw()

I can get the slider to work perfectly but I would like it to default to a value & marker at that value. I have tried the code component both before and after the slider component. Thanks.