reCaptcha - Asp.Net 3.1 - Site key cannot be null or empty

Question

I have two websites, installed reCaptcba on one, created the keys in Google and followed the guidance, putting the keys in web.config and appsettings.json. This works fine, I even found the keys that allow it to be tested on a local server. I then went to my second website and tried to do the same. This website had no web.config file so I created one and put the keys for the second website into it, also set up appsettings.json. However, when I tested the site on the local server it came up with the error 'InvalidOperationException: Site key cannot be null or empty.' when it hits the line @Html.RecaptchaWidget(). I then published the website and the same error occurred. I suspect that web.config is not be accessed, although it is there in both my local View folder and on the remote server. Assuming that this is where the problem lies, how do I get the key read? These are the lines from the web.config file:

 <appSettings>

<add key="RecaptchaSiteKey" value="Key as provided" />
<add key="RecaptchaSecretKey" value="Key as provided" />