Adding WebAPI as a child/nested application in IIS - asp.net

Question

Steps to recreate this issue:
Inside IIS create a new .net 4 website (herein known as the parent).
Drop a test image in the folder for this website and observe you can
request it successfully in a browser
Add a new virtual directory OR application under the parent that points to a WebAPI 2 project
Attempt to access the API in the browser using www.path-to-parent-site.com/api/something/or/other
I get the following error:
System.Web.Routing.UrlRoutingModule does not implement IHttpHandlerFactory or IHttpHandler.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Configuration.ConfigurationErrorsException: System.Web.Routing.UrlRoutingModule does not implement IHttpHandlerFactory or IHttpHandler.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[ConfigurationErrorsException: System.Web.Routing.UrlRoutingModule does not implement IHttpHandlerFactory or IHttpHandler.]
System.Web.Configuration.HandlerFactoryCache.GetHandlerType(String type) [phone]
System.Web.Configuration.HandlerFactoryCache..ctor(String type) +27
System.Web.HttpApplication.GetFactory(String type) +94
System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +375
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34209
Is there anything I can do to get this working? I can find very little relevant information on this particular issue and even fewer solutions to those who have seen this error.
Note: If I add the WebAPI 2 project as a new website in IIS it works perfectly; its only when its nested as a child (either virtual directory or application has the same problem) that this happens.
Thanks

Answer 1

WebApi is not supposed to be hosted on a virtual directory, if you wanna do so you need to make the routing pattern dynamic and load the first part from the virtual directory.
var virtualDirectory = request.ApplicationPath;
routes.MapHttpRoute(
name: "API Default",
routeTemplate: virtualDirectory + "/api/{controller}/{id}",
defaults: new {
id = RouteParameter.Optional
}
);

Answer 2

You need to use parentsite.com/childvirtualdirectory/api even though the API is hosted in the childvirtualdirectory.
In my scenario, I had parentsite/api setup in IIS... then to access the web API, I needed to use http://parentsite/api/api/<<controller>>