PHP has several configuration options to limit resources consumed by scripts. By default, PHP is set to allow uploads of files with a size of 2MB or less.
Try to increase limit by using .htacces file.
php_value upload_max_filesize 64M
php_value post_max_size 64M
php_value max_execution_time 300
php_value max_input_time 300
Try increasing the following values in php.ini, for example:
memory_limit = 32M upload_max_filesize = 24M post_max_size = 32M