Since the Subreport is in the Group Footer, you can't show the values in the Group Header.
To be able to show values from the Subreport, it has to be placed in a section above the section where you wish to show the values.
In this situation, you can create a Group Header 1b and place the Subreport in Header 1a while the Original Header is in the 1b section.
-Abhilash