Fatal error

Good Day, I searched but could not find a solution so here is the '
After system check second page results in:
Fatal error: Class ‘Piwik_Form’ not found in /home/content/c/a/c/cacheguy/html/piwik/plugins/Installation/FormDatabaseSetup.php on line 51
have re-installed twice

Piwik_Form is defined in core/Form.php. It depends on libs/HTML/QuickForm.php.

Check to make sure both of those files are there. (We’ve added a file integrity check to the upcoming version of Piwik.)