Fundraising heading error

When testing the fundraising plugin on a multisite install I get this error message when pledging a donation.

Warning: Cannot modify header information - headers already sent by (output started at /home/content/34/8757634/html/sites/modulemill/wp-content/themes/bp-corporate/header.php:6) in /home/content/34/8757634/html/sites/modulemill/wp-includes/pluggable.php on line 866

I have so far tested it on a wordpress single install.
I have also disabled all plugins while testing.
I have tested the plugin with other themes. I get the same message.

Cannot modify header information - headers already sent by (output started at /home/content/34/8757634/html/test/wordpress/wp-content/themes/PhoneTech/header.php:1) in /home/content/34/8757634/html/test/wordpress/wp-includes/pluggable.php on line 866

I have setup the paypal gateway.