Version: Tridion 2009
I have added a Custom Configuration section in Tridion.ContentManager.Config for storing some values to be used by the Custom Resolver that I'm writing.

I will use this value to detect whether the current publish transaction is executing against the live publication target or not.

However, when I attempt to retrieve the values from the config file, I get "Object reference not set to an instance of an object." error.

This is how the configuration looks like:

    <configuration>
        <configSections>
            <!-- Other Config Section Declarations -->     
            <section name="My.ConfigSection" 
                     type="System.Configuration.NameValueSectionHandler" />
        </configSections>
        <My.ConfigSection>
                <add key="LivePublicationTargetId" 
                     value="tcm:0-10-65537" />
        </My.ConfigSection>
        <!-- Other Config Sections-->
    </configuration>

This is how I try to retrive it from the IResolver class: (Please note that this is working for regular ASP.net websites.)

string LivePubTargetID = ((NameValueCollection)ConfigurationManager.
       GetSection("My.ConfigSection")).Get("LivePublicationTargetId");

This is the piece that returns null and causes the error: ConfigurationManager.GetSection("My.ConfigSection").

Any ideas about how to overcome this issue?