In order for the URL mappings to work in Subtext, you need to configure a custom "404 Not Found" page for it. Unfortunately, that's not something the application can do for you so this is a manual process.
In an environment where you have console access to your web server (e.g., you can connect via Remote Desktop), the custom 404 page gets set through the IIS management console. This is the process described here.
If you do not have console access (e.g., you go through a hosting provider such as GoDaddy), there is generally a web-based interface that provides the same functionality. Either way, it should be a similar process to the one described below.
- Open up the IIS Management Console.
- Right-click the application that contains the Subtext blog (which may be the root application on your server) and select "Properties."
- Select the "Custom Errors" tab.
- Scroll down and select the "HTTP Error" number 404.
- Click the "Edit Properties..." button.
- Enter "URL" for the "Message Type" and
/SystemMessages/FileNotFound.aspx in the URL field. (Note: If the Subtext software is not installed in the root of the web server, you may need to modify this path. For example, if Subtext is installed in the "Blog" subfolder, the path would be
/Blog/SystemMessages/FileNotFound.aspx - adjust for the install location.)
- Click OK to apply the changes and then OK again to close the application properties dialog.
Again, if you are using a hosting provider and do not have access to the IIS Management Console, your provider should have a web-based interface for you to do this same operation, though the steps may be slightly different.