Adding Virtual directory under DNN website ,

I want to create virtual directory in my DNN website and make new database for this site , for this I go to IIs manager and click add virtual directory and browse that site it shows error

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

Module IIS Web Core Notification BeginRequest

Handler Not yet determined

Error Code 0x800700b7

Config Error Cannot add duplicate collection entry of type 'add' with unique key attribute 'name' set to 'LogoffHandler*'

Config File \?\C:\Website\dnndev.me\web.config

Requested URL http://www.dnndev.me:80/VirtualDnn Physical Path C:\Website\dnndev.me Logon Method Not yet determined

Logon User Not yet determined Config Source 116:

117:

118:

Please tell me how can i resolve this problem ........

Thanks

You might need to add

<location inheritInChildApplications="false">

To your web.config file so that DotNetNuke stops handling requests to that virtual directory.

Something along the lines of what is mentioned in this answer https://stackoverflow.com/a/782277/21362

An old blog post I wrote might also help

http://www.dotnetnuke.com/Resources/Blogs/cid/135153/DotNetNuke-Tip-15-Running-a-webservice-inside-of-a-DNN-site.aspx