No Apex class named 'ParkService' was found. Ensure the class you generated from the WSDL is named 'ParkService'.

Hello @Bhavana Dubey

The WSDL2Apex generator automatically suggests a default class name that doesn't match what the challenge validator expects. To fix this, you must override the auto-generated name when parsing the WSDL file.

For me, WSDL2Apex generated the class as parkServices, not ParkService. Changing the name of the WSDL-generated class to ParkService worked for me.  

Hope that helps!