paypal sandbox error message

I am in the process of setting up paypal sandbox; follow paypal’s developer directions on creating business and two personal accounts; input the business credentials (copy/paste w/o spacing, triple checked) into funding/paypal information; repeated this process approximately 10 times, read copious paypal troubleshooting information on this forum and on others; even use the sandbox information provided from one of the responses posted by this forum; and still faithfully get the same error message when I test the funding process:
Warning: error_log() expects parameter 2 to be long, string given in /usr/local/php55/pear/Log/error_log.php on line 153

Fatal error: Class ‘FatalException’ not found in /home/itsybit2/public_html/wp-content/themes/funding_press/funding/lib/PayPal/CallerServices.php on line 80

Any advise on how to proceed would be greatly appreciated.