Calling External Assemblies which require there own condig setting

Hi,
I've successully called a method of an external assembly (which is part of a
large web-based application) from within the report designer.
However, when I call a different method from the same external assembly I
get an error "Failed to load expression host assembly. Details : The
ConnectionString property has not been initialized".
Now I know the Details part of the error is coming from the external
assembly. Looking at it's code it's calling another assembly and attempting
to set a connection string so that it can access it's own database. The value
of the connection string usually comes from a Web.Config file.
My question is how does .NET decide which config file to search in this
case? I've tried placing the connection string part in machineconfig and
RSReportDesigner.config.
Haven't done code access securiy yet as, according to Teo's book Reporting
Services in Action, when you preview a report it assigns it full trust.
Cheers.
MartinHi,
A colleague of mine pointed out that the entries I made to machine.config
were commented out. Once uncommented it now works!
Still, would be nice to know what's happening re .NET searching for config
files.
Cheers,
Martin