Cannot modify header information - headers already sent (Yes, another one of these)

I followed the Web development tutorial: Create a product catalog eCommerce series. Sadly, the following error whenever adding/updating to the dB has plagued me:

( ! ) Warning: Cannot modify header information - headers already sent by (output started at C:\wamp\www\test\Connections\clubquarters.php:6) in C:\wamp\www\test\admin\admin_insert.php on line 65

There are many posts on this subject, and I believe I read and followed all of them. I removed all the spaces/line breaks in the php, as well as all the notes. I removed and reinstalled DataBridge and eCart, and made sure DW is updated. Additionally, I re-ran through the tutorial numerous times and had the same result each time when adding/updating to the dB. Included is the insert.php and connections php pages noted in the Warning, though it occurs on update and when I try to add to cart.

Is it a problem with the placement of the $WA_redirectURL? Does it need to be higher in the code? Is it a problem with using WAMP? (I will sorely be disappointed in myself if you see a space/extra line that I missed causing the error. Like everyone else with this error, which I am certain you are sick of seeing, I spent many hours trying to fix it myself.)

Any assistance is greatly appreciated.