The exact solution to your problem will depend on what configuration exception message you are seeing. However, this is a typical problem that can often be solved through use of the inheritInChildApplications attribute on the location element in the web.config for “WebParent”. By wrapping the entire system.web section in a location element as follows, you should be able to eliminate the problem you described:
<location path="." inheritInChildApplications="false">
<system.web>
<!-- ... -->
</system.web>
</location>
With IIS 7, you will also want to wrap the system.WebServer section the same way:
<location path="." inheritInChildApplications="false">
<system.webServer>
<!-- ... -->
</system.webServer>
</location>
This solution is based on an excellent blog article that I found here.