Good everybody, I'm trying to use MoodleExcelWorkbook for my plugin but it seems impossible, so I would like to know if there is someone who could help me.
The problem I have is that when I hit the download button I get the error 'headers already sent by'. I know this happens because the send() function of MoodleExcelWorkbook sends new headers to the header but in my .php which is rendered first I do "echo $OUTPUT->header();" so the headers have already been sent. I tried to remove "echo $OUTPUT->header();" but then I can't render the page.
I've attached some screenshots of the code in case it helps.
So I know the problem but not the solution. If someone would be so kind to help me I would appreciate it.
Thank you very much in advance
externallib.php
porcentage.php
