Why does this managed ODP.NET LDAP connecion attempt throw an OracleInternal.Network.AddressResolution?

Question

I am trying to use the new managed OPD.NET driver version 4.121.1.0

This my appconfig file, The settings are copied from the ldap.ora

<configSections>
    <section name="oracle.manageddataaccess.client" type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess"/>
</configSections>
<oracle.manageddataaccess.client>
    <version number="*">
        <LDAPsettings>
            <LDAPsetting name="DIRECTORY_SERVERS" value="oid1.xxx.com:389:636, oid2.xxx.com:389:636, oid3.xxx.com:389:636" />
            <LDAPsetting name="DIRECTORY_TYPE" value="OID" />
            <LDAPsetting name="DEFAULT_ADMIN_CONTEXT" value="cn=OracleContext,dc=xxx,dc=com" />
        </LDAPsettings>
    </version>
</oracle.manageddataaccess.client>
<connectionStrings>
    <add name="MYDB" connectionString="Data Source=MYDB;User Id=MYUSER;Password=mypassword;" />
</connectionStrings>

It throws this:

1. exception is TypeInitializationException in OracleInternal.Network.AddressResolution
2. inner exception is TypeInitializationException in OracleInternal.Network.LDAP
3. inner exception finally has a NullReferenceException in the OracleInternal.Network.LDAP.ctor
   • at OracleInternal.Network.LDAP._LDAP(Hashtable dsMap)
   • at OracleInternal.Network.LDAP..cctor()

when I try to open a connection.