Redirect issue - Cannot modify header information (already checked for blank lines)

Hi,

My page is not redirecting properly after an update. I've viewed multiple postings in the forums about this and tried different solutions, all with no luck. I've also double checked that there are no blank lines between opening and closing PHP tags and after 30 minutes of examining the code I can't see any.

I've turned all error reporting on and the exact error I'm getting is:

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/esm.uk.com/public_html/esmfreelancers/assignments-update.php:77) in /home/sites/esm.uk.com/public_html/esmfreelancers/assignments-update.php on line 186

I've looked at line 77 in the code and that's a security assist check to make sure the user is logged in. I tried removing that piece of code, but I still get the error. I've also looked at line 186 - that's the line that tells the page to re-direct. Nothing I can see wrong there either.

I've attached a copy of my page. If someone could help me with this I'd be most grateful.