AddDeviceProfileReq do not work

Hi I'm using AxlToolkit scheme 8.0

I try add new device profile to cucm (version 8+)

I get exception type of InvalidOperationException with that message  "There was an error generating the XML document".

What am I do wrong?

        public void addDeviceProfile(ref AXLAPIService reference_approved, Person person)

        {

            AddDeviceProfileReq deviceprofilereq = new AddDeviceProfileReq();

            StandardResponse res = new StandardResponse();

            XDeviceProfile deviceprofile = new XDeviceProfile();

            XPhoneButtonTemplate phonebuttontemplate = new XPhoneButtonTemplate();

            XFkType softkey = new XFkType();

            XFkType linepartition = new XFkType();

            XDeviceProfileLines deviceprofilelines = new XDeviceProfileLines();

            XLine line = new XLine();

            linepartition.Value = "Local_PT";

            softkey.Value = "Standard User";

            phonebuttontemplate.name = "Standard 7861 SIP";

            line.pattern = "6499262";

            line.routePartitionName = linepartition;

            line.alertingName = "New Line";

            line.asciiAlertingName = "New Line";

            object[] line_items = new object[2];

            line_items.SetValue(line, 0);

            deviceprofilelines.Items = line_items;

            deviceprofile.softkeyTemplateName = softkey;

            deviceprofile.name = person.ipphone;

            deviceprofile.description = person.alias + " " + person.ipphone;

            deviceprofile.protocol = "SIP";

            deviceprofile.product = "Cisco 7861";

            deviceprofile.protocolSide = "User";

            deviceprofile.@class = "Device Profile";

            deviceprofile.lines = deviceprofilelines;

            deviceprofilereq.deviceProfile = deviceprofile;

            try

            {

                res = reference_approved.addDeviceProfile(deviceprofilereq);

            }

            catch

            {

                ;

            }

        }

OK I forgot to add the phonetemplate