Here are some lines for a DNN expert 
The problem radicates in a null object reference exception. I do not know why these object (objAuthenticationController), instance of AuthenticationController is null or simply could not recognize his childs... It raise an error when the NetWorkStatus method is called and asigned to a variable... may be something related to credentials and security?
(this code is from the page AuthenticationSettings.ascx.vb, line 129)
Please... HELP! 
Sub cmdAuthenticationUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdUpdate.Click
Dim _portalSettings As PortalSettings = CType(HttpContext.Current.Items("PortalSettings"), PortalSettings)
Try
Dim providerTypeName As String = Me.cboProviders.SelectedItem.Value
Dim authenticationType As String = Me.cboAuthenticationType.SelectedItem.ValueMe.chkAuthentication.Checked, Me.txtRootDomain.Text, Me.txtEmailDomain.Text, Me.txtUserName.Text, Me.txtPassword.Text, Me.chkSynchronizeRole.Checked, Me.chkSynchronizePassword.Checked, providerTypeName, authenticationType)
Configuration.ResetConfig()Dim objAuthenticationController As New AuthenticationController
Dim statusMessage As String = objAuthenticationController.NetworkStatus
If statusMessage.ToLower.IndexOf("fail") > -1 Then
MessageCell.Controls.Add(UI.Skins.Skin.GetModuleMessageControl("", LocalizedStatus(statusMessage), DotNetNuke.UI.Skins.Controls.ModuleMessage.ModuleMessageType.RedError))
Else
MessageCell.Controls.Add(UI.Skins.Skin.GetModuleMessageControl("", LocalizedStatus(statusMessage), DotNetNuke.UI.Skins.Controls.ModuleMessage.ModuleMessageType.GreenSuccess))
End If
Catch exc As Exception 'Module failed to load
ProcessModuleLoadException(Me, exc)
End Try
End Sub
Configuration.UpdateConfig(_portalSettings.PortalId,