Thanks that is very honest of you to not push the source. :)

The checkbox is on, and I looked in the hostsettings table in DB too to confirm it is set to 'Y'.  We are using DNN 4.9.0 with the newest Localizator version. Is there anything else that the 'Install hack' option does than add the reference:

 Inherits Delisoft.DNN.PageBases.MyLocale : Implements IClientAPICallbackEventHandler      ?

I tried reinstalling the hack but no change.. it could be that we have modified the default.aspx.vb or something else for an unrelated hack - maybe the caching has been impaired by this, or is the logic contained in the .DLL?

Thanks