Thanks for responding Ian and Jason. I thought the file size might be the issue and I had set the upload_max_filesize to 20M and php_value post_max_size to 22M on my local machine.
After seeing your posts I looked into size problems again and I was able to get it to work using an .htaccess file to set the upload and post sizes.
That's when I realized I had forgotten to restart wampserver. All is well now.
Thanks for your help!