Insert new key into appSettings.config

[paxil]

I want to be able to add a new key to the appSettings.config file. I can do the write xml and update existing entries no problem, but cannot add new lines? Any help would be much appreciated.

For example:

Before the add:
<appSettings>
<add key="DatasourceConnection" value="server" />
</appSettings>


After New Key added:
<appSettings>
<add key="DatasourceConnection" value="server" />
<add key="LDAPBinding" value="NEW KEY" />
</appSettings>