I get this when I tried to activate after installing:
Warning: Cannot modify header information - headers already sent by (output started at /home/foxmusi1/public_html/foxboromusic.com/website/wp-content/themes/twenty-leven-kid-1/functions.php:8) in /home/foxmusi1/public_html/foxboromusic.com/website/wp-content/plugins/font-uploader/font-upload.php on line 83
When I returned to the plug in page, it seemed to be installed, but when I tried to upload a font I got the same message. I also go it when I tried to deactivate.
TwentyLevenKid1 is my child theme based on Twenty Eleven.