You need to check folder permissions on your upload folder,

UPLOAD FOLDER Needs to be Unix 0777
RWX RWX RWX

On un*X go the folder above the upload/

EXAMPLE
If the upload folder sits in an folder off your web root, change to the root of that directory, the parent of the upload folder.

cd /usr/local/apache/htdocs/applicationname…

type:

chmod 777 upload

Review the README and INSTALL file of the application you installed, there may be other folders on which you need to check permissions.

Could be file size, there are parameters in APACHE and PHP that may require modifications. I set my php.ini to allow up to 40 mg uploads and parallel that in httpd.conf.