Its likely not getting to the server because of the size
http://www.php.net/manual/en/features.file-upload.common-pitfalls.php
The MAX_FILE_SIZE item cannot specify a file size greater than the file size that has been set in the upload_max_filesize in the php.ini file. The default is 2 megabytes. If a memory limit is enabled, a larger memory_limit may be needed. Make sure you set memory_limit large enough. If max_execution_time is set too small, script execution may be exceeded by the value. Make sure you set max_execution_time large enough