1&1 install

We're having some trouble installing on a 1&1 shared host under a sub-domain... Perch Runway says you're all set. 1&1 is running MySQL5.5, could be related "Please note that PHP 5.5 and later versions do not support MySQL. Please use the MySQLi". Changed perms on all files, got set-up form to show, it seemed to work then failed. Reuploaded all files in perch_v2.8.34 now getting Fatal error: Class 'Perch' not found in /homepages/24/*****/htdocs/*******/perch/setup/index.php on line 39 Any pointers?