I created an application in XCode 4 that uses Core Plot.
I installed Core plot as an aditional SDK following the instructions from here:http://code.google.com/p/core-plot/w
I had the same issue for both TestFlight and App Store.
The solution for me was to archive the app, and in the organizer select "Don't sign" when you try to validate/submit or share (in the case of TestFlight).