Run nopCommerce on virtual directory on Azure

I have been running DNN 7 on Azure using some store module that we have grown out of. We are in the process of moving our store to nopCommerce. But since we have so much content, other than the store on the DNN site, we would to explore keeping the DNN site and setting up a virtual directory with nopCommerce and run them both under the same domain name.

I have configured the virtual directory MyDNNPortal.AzwureWebSites.net/store to point to the physical folder "site_nopCommerce" and checked the "application" checkbox.

DNN works fine, but when trying to navigate to MyDNNPortal.AzwureWebSites.net/store, I get the following error:

"The page cannot be displayed because an internal server error has occurred."

This error is just those words in black on a white screen. It is not the typical IIS error.

I have customErrors set to off in both the DNN app and the nopCommerce app. I have the show detailed errors option checked in the Azure config for the DNN website. But that is the only error I get.

If I go to the LogFiles folder via FTP, there is an errorpage000001.htm page that sheds some more light:

HTTP Error 500.19 - Internal Server Error
The requested page cannot be accessed because the related configuration data for the page is invalid.
Error Code 0x80070003 

Config Error
   Cannot read configuration file  

Config File
   \\?\D:\home\site\_nopCommerce\web.config 


Requested URL
   http://mywebsite:80/store 

Physical Path
   D:\home\site\_nopCommerce 

Any ideas? Is this structure possible (running nopCommerce in a virtual directory within a DNN site)? I've seen this error on my localhost and then add IIS_USERS permissions to fix...but I am not aware of the ability or need to configure those types of permissions on Azure.