Check and make sure the folder you are uploading to has the proper permissions, you can do this with a simple chmod r 777 command. May I suggest permission on the upload folder be 775. This should give both the apache and FTP users the ability to write to the files in the folder but keep everyone else from modifying them.
You can always checked the (move_uploaded_files)'s ['error'] index for any errors that you may experience. If it is 0, then your upload was successful.
Check out this article if you need more information, http://www.w3schools.com/php/php_file_upload.asp