Failing to display a list of methods even when the wsdl file loads successfully


Assist with this issue.
I want to use WebServiceStudio to test a web service. After specifying the location of the end point WSDL file and click get, the file loads successfully. This i the message I get on the messages.
Generating WSDL
Generating Proxy
Compiling Proxy
Generated Assembly
Reflecting Proxy Assembly
Ready To Invoke

However when I go to the Invoke method, The methods are not displayed. There is nothing displayed. This does not happen on all webservices I want to test. I am able to connect public webservices on the Internet. Other testing tools like SoapUi are able to connect to this webservice.
What do I need to configure on my environment?