WCF Service not invoked

Question

I have a problem while calling a WCF Method.

The program steps correctly into ProxyX3Service.cs, and now it should invoke the WCF method (ProxyX3Service.svc.cs).

ProxyX3Service.cs:

public async static Task<CambioUbicazione> GetArticoloFromInput(ProxyX3ServiceClient client, string input)
        {
            return client.GetArticoloFromInput(ProxyX3Service.SessionId, input);
        }

ProxyX3Service.svc.cs:

public CambioUbicazione GetArticoloFromInput(Guid sessionId, string input)
        {
            //db.RefreshSessionV6(sessionId);
            logger.Info("Method begin");
            
            var query = (from item in db.ITMMASTER
                         join stock in db.STOCK
                         on item.ITMREF_0 equals stock.ITMREF_0
                         where (item.ITMREF_0 == input || item.EANCOD_0 == input || stock.SERNUM_0 == input)
                         select new CambioUbicazione
                         {
                             Articolo = item.ITMREF_0,
                             GiacenzaX3 = stock.QTYSTU_0 - stock.CUMALLQTA_0 - stock.CUMWIPQTY_0,
                             UbicazioneX3 = stock.LOC_0
                         });

            logger.Info(query.ToString());
            return query.FirstOrDefault();
        }

But it doesn't work: it doesn't step even in the logger method.

This is the interface IProxyX3Service.cs

[OperationContract]
        CambioUbicazione GetArticoloFromInput(Guid sessionId, string input);

Same method with apparenctly the same structure works, only this method have some problems.
Thanks for every help!