Use the config.php file instead of the .htaccess
Add the following line with your own limit in your config.php file of your root directory.
You can also define the memory_limit in your .htaccess file:
php_value memory_limit 256M
Verify your changes
Create a php file and paste the following line:
It will show the PHP Info, including the memory_limit (local and master values)
(use the search function in your browser to find it).