Warning: Cannot modify header information - headers already sent

[pavel]

I am getting this error:\[code\]Warning: Cannot modify header information - headers already sent by (output started at E:\www\dev\elearning1\WebProjects\elearning\public\test.php:1) in E:\www\dev\elearning1\WebProjects\elearning\public\test.php on line 3\[/code\]This is my entire PHP file: \[code\]<?phpheader('Content-Type: text/html; charset=utf-8');// set the include pathset_include_path(dirname(__FILE__).'/../../../WebLibThirdParty/Zend/library');function __autoload($class) { require_once(str_replace('_', '/', $class) . '.php');}// Create new PDF $pdf = new Zend_Pdf();$page = new Zend_Pdf_Page(Zend_Pdf_Page::SIZE_A4);// Set font $page->setFont(Zend_Pdf_Font::fontWithPath('times.ttf'), 12); // Draw text$string = '?kola vol