Curl errorr

hello guys i am using facebook socialite . when the user is redirect the following error is occur :

"cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)"

i download the pem file and place it php.ini there is following path of file . curl.cainfo ="C:\xampp\php\extras\ssl\cacert.pem" but still the error is occur how i can fix it. Thanks :)