Error after trying to make admin as friend

I just tried to make admin friend everyone by modifying the file BxDolJoinProcessor.php 
when I tried to join I received the error: 
Warning: Cannot modify header information - headers already sent by (output started at /home/ahealthy/public_html/dolph/inc/classes/BxDolJoinProcessor.php:651) in /home/ahealthy/public_html/dolph/inc/design.inc.php on line 133

I put the file back to the original & still have the error. i hadnt tried the join button before making the mod, but it would be quite a coincidence if the error was there before i messed with it. Any ideas?

BTW..I did clear out cookie with no change to the issue.

check if there are extra line in file after ?> in bottom

There was 2 extra lines at end of file. I removed them & now it works.

Thanks you for helping. I would never have figured out that one.

Can you explain what the problem was.

The problem is because there are some content(blank lines) that are send to browser before the header is send.

I have encountered this with Dolphin files.  You open the file and don't make any changes to the end of the file; save it out and get the headers already sent error.  Open the file back up and bam, there are blank spaces or lines at the end of the file.  Is it that for some strange reason opening the file inserts these lines; I don't get this every time I open files?  Or is it that the lines existed in the file before I open it and for some strange reason did not cause the headers sent error until I opened and saved the file?  I am just curious as to why this happens.

not sure but might occur due to ftp transfer in ASCII mode but again i am not very sure.

It looks like is is related to Dolphin 7.0.

In Dolphin 7.1 we removed every closing php tag at the end of file to prevent problems like in this thread.