Are there any other settings besides php.ini to allow file upload?
Please read through this documentation:
https://www.drupal.org/node/97193

Depending on your HTML form and server configuration if you have a 1MB filesize limit; uploaded files close to your maximum filesize may not successfully upload to a webserver because a file is sent as apart of a multi-part HTTP transmission.

You want to assure post_max_size is typicaly 2x or 3x larger than your upload_max_filesize. Brief discussion on this can be found here:
https://stackoverflow.com/a/15077229/1491507

Googling PHP maximum post size and file sizes should lead to similar documentation on php.net and other resources.