New Post: CONTENT LOCALIZATION ISSUE

Hello,
my website is multilingual Italian - english
When try to click on english flag on shop page get this error:
Shop is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at NEvoWeb.Modules.NB_Store.ProductTemplate.AddToRelated_DataBinding(Object sender, EventArgs e) at System.Web.UI.Control.OnDataBinding(EventArgs e) at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) at System.Web.UI.Control.DataBind() at System.Web.UI.Control.DataBindChildren() at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) at System.Web.UI.Control.DataBind() at System.Web.UI.WebControls.DataList.CreateItem(Int32 itemIndex, ListItemType itemType, Boolean dataBind, Object dataItem) at System.Web.UI.WebControls.DataList.CreateControlHierarchy(Boolean useDataSource) at System.Web.UI.WebControls.BaseDataList.OnDataBinding(EventArgs e) at System.Web.UI.WebControls.BaseDataList.DataBind() at NEvoWeb.Modules.NB_Store.ProductList.populateList(Int32 CatID) at NEvoWeb.Modules.NB_Store.ProductList.Page_Init(Object sender, EventArgs e) --- End of inner exception stack trace ---

Articles in NBStore module are all multilingual,portal well-translated and language pack installed.
The only issue is with the product list module.
Sometime,when try to click on specific category ,it works. Sometimes not.
There is a way to fix this?=
Thank you!