asp.net mvc - Getting Error Code 400 Bad Request While Connecting to my Quickbook API V3 Sandbox Company in nopcommerce V3.60? -

i sending order item quickbooks sandbox account online using api keys , tokens. when searching product online , gives error code 400 exception bad request.

 // sending order item quickbook online account            [nonaction]             public void postorderpos(order order)             {             string accesstoken = "qyprd9yjd4unmlr3zcrcw8zfdjs9wwtgm71oh3t2pzbsc8cb";             string accesstokensecret = "srsbyb9iynyywfjaxxl4zlavjjl8hpfw0an3swra";             string consumerkey = "qyprdwz4vag2knd4e1aehqaufcchpm";             string consumersecret = "bvormln4y7h5cg9na0ov27pqyb9bzsucmiyurt70";             oauthrequestvalidator oauthvalidator = new oauthrequestvalidator(accesstoken, accesstokensecret, consumerkey, consumersecret);             string apptoken = "bd0a230bb9dc9b4321ba9feb899e18471d58";             string companyid = "1403414765";  // realm             servicecontext context = new servicecontext(apptoken, companyid, intuitservicestype.qbd, oauthvalidator);             dataservice service = new dataservice(context);              invoice inv = new invoice();             inv.autodocnumber = true;             inv.autodocnumberspecified = true;              line[] lines = new line[order.orderitems.count + 2];             int count = 0;             foreach (var orderitem in order.orderitems)             {             line line2 = new line();             line2.description = orderitem.product.getlocalized(x => x.sku);             line2.detailtype = linedetailtypeenum.salesitemlinedetail;             line2.detailtypespecified = true;             line2.amount = _currencyservice.convertcurrency(orderitem.priceexcltax, order.currencyrate);             line2.amountspecified = true;              item qboitem = new item();             var productname = orderitem.product.getlocalized(x => x.name).tolower();              ienumerable<item> qboitems = service.findall(qboitem).where(x => x.name.tolower() == productname) ienumerable<item>; // ***-- here getting error***              int productid = 0;             if (qboitems.count() > 0)             {             productid = convert.toint32(qboitems.firstordefault().id);             }             else             {             item product = new item();             product.name = orderitem.product.getlocalized(x => x.name);             product.description = orderitem.product.getlocalized(x => x.sku);             product.active = true;             product.activespecified = true;             product.assetaccountref = new referencetype()             {             name = "inventory asset",             value = "54"             };              product.unitprice = _currencyservice.convertcurrency(orderitem.unitpriceexcltax, order.currencyrate);             product.unitpricespecified = true;             product.type = itemtypeenum.inventory;             product.typespecified = true;              referencetype refproduct = new referencetype();             refproduct.name = "sales of product income";             refproduct.value = "52";             product.incomeaccountref = refproduct;             var addedproduct = service.add(product);             productid = convert.toint32(addedproduct.id);              }             }              inv.shipdate = datetime.now.adddays(7);             inv.shipdatespecified = true;              invoice invoiceadded = service.add(inv);             } 

in servicecontext change line intuitservicestype.qbd intuitservicestype.qbo