Cannot instantiate abstract class

[Harvey13]

Hello,

I tried to rum the onvifclientwin32 project but got some error claiming about virtual definitions.

Error C2259 'OnvifClientEventNotify': cannot instantiate abstract class onvifclient c:\devsoap\onvifcpplib\example\client\onvifclientwin32\onvifclient.cpp 69

I tested it with MSVC2015

1>c:\devsoap\onvifcpplib\example\client\onvifclientwin32\onvifclient.cpp(69): error C2259: 'OnvifClientEventNotify': cannot instantiate abstract class
1>  c:\devsoap\onvifcpplib\example\client\onvifclientwin32\onvifclient.cpp(69): note: due to following members:
1>  c:\devsoap\onvifcpplib\example\client\onvifclientwin32\onvifclient.cpp(69): note: 'int PullPointSubscriptionBindingService::PullMessages(_tev__PullMessages *,_tev__PullMessagesResponse &)': is abstract

virtual int PullMessages(_tev__PullMessages *tev__PullMessages, _tev__PullMessagesResponse *tev__PullMessagesResponse) 
    {return SOAP_OK;}

What can I do ?
Thanks in advance!