Error: Shopping cart is empty - Zen Cart

I had a weird issue today, while adding a item to client's Zen cart; it gave me the error below even though I added an item to it.

Shopping cart is empty

I found that it was because the output_buffer attribute in php.ini is turned off. You have to options to fix this:

1. Get system administrator turn the attribute output_buffer 'on' in php.ini.

OR

2. Create php.ini in all the folder, which requires this attribute (I was not sure which folder would require, so I created the php.ini in the main shop directory, admin/ and includes), with the below contents.

output_buffering = On