I try to bulk create the content, one of the property is a vorto textstring

here is the code, when call the SetValue content an error occur

"UMBRACO The best overloaded mthod match for 'Umbraco.Core.Models.ContentBase.SetPropertyValue(string, string)' has some invalid arguments"

anybody can help with this, thanks a lot

var cs = _applicationContext.Services.ContentService;
var dts = _applicationContext.Services.DataTypeService;
Guid vortoTextstringGuid = dts.GetAllDataTypeDefinitions().Where(x => x.Name == "Vorto Textstring").FirstOrDefault().Key;

var newContent = cs.CreateContent(name: "newItem, parentId: 6500, contentTypeAlias: "itemTypeAlias", userId: 0);


VortoValue newVortoItem = new VortoValue();
 newVortoItem.Values = new Dictionary<string, object>();
                        department.Values.Add("en-US", (object)"English");                        
                        department.Values.Add("zh-HK", (object)"Chinese");
newContent.SetValue("ItemPropTypeAlias", (object)newVortoItem );

cs.Save(newContent);