Im using zoho php sdk with a custom token persistence class but it always tells me class not found

Im using zoho php sdk with a custom token persistence class but it always tells me class not found

Followed the instructions here https://www.zoho.com/crm/developer/docs/php-sdk/token-persistence.html#custom

However even if the class does exist, i always get an error from ZohoOAuth.php line 141 
`Class 'CustomPersistence' not found`

This is weird because it pases the require_once statement in line 139.