PluginInitializationError- Error registering Urls for plugin

Judging by the error, the your IApplicationType class has not also implemented INavigableApplicationType Plugin Type  

No I Implemented it. it's has only method,  public string PathDelimiter => "/a/";

Only 3 possibilities I can see:

• The application does not implement INavigableApplicationType
• The plugin for the application type is not enabled in the community.
• The applicationTypeId is different between your IApplicationType and IApplicationNavigable implementations.

Thank you for your reply.

I Implemented INavigableApplicationType, enabled application type in Administration-->Extension, also verified ApplicationTypeId it's same.

but urlFormatting.FormatGroupUrl always returns null, Kindly refer the above image, I'm passing, page name, group and dictionary with applicationkey as parameters, Is that right? Kindly guide me.

What's the full namespace for ApplicationUrls? use of non-extensible classes and services is not recommended. Instead try using the Url Api's BuildUrl method: community.telligent.com/.../url-in-process-api-service