ASP.NET 2.0 AJAX client side JavaScript webservice call error 'type is undefined'

I am using I have a web app that calls a webservice from client side JavaScript. In a user control I am using a server side dropdownlist with
a client side attribute onchange for the onchange event (onchange="OnCountryChange(this);"). When the selected country changes, the webservice needs to be called to get the regions belonging to the selected country.

I use the following code:


function OnCountryChange (countryCtrl) {
MyNamespace.Web.Services.CountryService.set_defaultSucceededCallback (OnCountryChangeComplete);
MyNamespace.Web.Services.CountryService.set_defaultFailedCallback (OnError);

var countryId = parseInt (countryCtrl.options [countryCtrl.options.selectedIndex].value);

MyNamespace.Web.Services.CountryService.GetRegions (countryId, OnLookupComplete, OnError);
}
All works fine locally. When I upload it to my Windows 2008 production server, ...