Change the color of the Header bar in a report

I have a cubeview that is run in a reporting book. I have created a Cubeviewer extender rule to change some formatting. For example, to put a different logo on the report based on the entity. It works fine. On the report there is also a header line and I can adjust the header line height by the following code 

ElseIf uiItem.UIItemType = XFReportUIItemType.PageHeaderLabelBar Then
uiItem.Height = 1

I also wanted to change the color to the company color. But it does not do it, I used uiItem.Bordercolor. But it keeps it black (See below picture, what I am looking for). Does somebody know how to do this?