It seems like if you're missing a few tags...

Here's what the Northwind's Sample Application has:

<?xml version="1.0" encoding="Windows-1252"?>
<configuration>
  <configSections>
    <section name="databases" type="System.Configuration.NameValueSectionHandler" />
    <section name="databaseSets" type="System.Configuration.NameValueSectionHandler" />
  </configSections>
  <appSettings>
    <!--   User application and configured property settings go here.-->
    <!--   Example: <add key="settingName" value="settingValue"/> -->
    <add key="SecurityDatabaseSetKey" value="CustA" />
    <add key="SecurityDatabaseKey" value="Northwind" />
    <add key="DatabaseSetDefault" value="CustA" />
    <add key="EventLog\Level" value="Verbose" />
    <add key="EventLog\Machine" value="." />
    <add key="EventLog\Name" value="Application" />
    <add key="TraceLog\Level" value="Verbose" />
    <add key="TraceLog\Machine" value="." />
    <add key="TraceLog\Name" value="Application" />
    <add key="TransactionLog\Level" value="Verbose" />
    <add key="TransactionLog\Machine" value="." />
    <add key="TransactionLog\Name" value="Application" />
    <add key="LocalizeApp" value="true" />
    <add key="SecurityEnabled" value="true" />
  </appSettings>
  <databaseSets>
    <add key="CustA" value="Customer A (SQL Server)" />
    <add key="CustB" value="Customer B (Visual FoxPro)" />
  </databaseSets>
  <databases>
    <add key="CustA\Northwind\Connection" value="server=(local);uid=sa;pwd=;database=Northwind;" />
    <add key="CustA\Northwind\DataAccessClass" value="DataAccessSql" />
    <add key="CustB\Northwind\Connection" value="Provider=vfpoledb.1;Data Source=C:\Program Files\Mere Mortals .NET Framework\Samples\VFPData\northwind.dbc" />
    <add key="CustB\Northwind\DataAccessClass" value="DataAccessOleDb" />
  </databases>
  <system.windows.forms jitDebugging="true" />
</configuration>