New Post: How can I change progress bar value in BusyIndicator?

After looking around and trying a few things, I finally found the solution here:

http://stackoverflow.com/questions/12515710/problems-with-binding-data-to-data-templates-inside-a-busyindicator

When binding, use RelativeSource and then refer to its DataContext and the appropriate property. In my case (I am using Caliburn.Micro and had to search for UserControl, not Window when searching for the Ancestor):

<ProgressBar Value="{Binding Path=DataContext.TaskProgress, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}" />

(Although it is an old thread, I decided to put the info here because google returns this page as the first one in the search I used... Hopefully it helps others...)