Amazon Product in Post error

I am new user and i have installed Amazon Product in Post plugin and after posting a product in it, i got following error. I have also changed API get method to curl, and in curl method instead of error, i see just blank.
does any body know how to correct it?

Warning: file_get_contents(https://webservices.amazon.com/onca/xml?AWSAccessKeyId=XXXXXXXXXXX&AssociateTag=xxxxxxx-20&IdType=ASIN&ItemId=B003WGZZDQ&Operation=ItemLookup&ResponseGroup=ItemAttributes%2CImages%2COffers%2CReviews&Service=AWSECommerceService&Timestamp=2013-04-19T09%3A04%3A37Z&Version=2011-08-01&Signature=XXXXXXXXXXXXXXXXXX) [function.file-get-contents]: failed to open stream: Permission denied in /home/www/fxxxxxxxxxxx.us/wp-content/plugins/amazon-product-in-a-post-plugin/inc/aws_signed_request.php on line 376