Forum Post: Unknown validation problem

We have a Webservice that connects to Sage50 Accounting 2014. When running this webservice through visual studio (IIS Express) it works just fine! But when running through IIS 7.0, We got "Granted" when requesting the access, but when trying to open the company, We got "Unknown validation problem" error messsage! Here is my code:                 //create and initialize Sage50 session                 PeachtreeSession sage50Session = new PeachtreeSession();                 //begin session                 sage50Session.Begin(applicationId);                 //get company identifier                 CompanyIdentifier myCompanyIdentifier = GetCompanyIdentifier(sage50Session, Configurations.Sage50CompanyName);                 //request authorizaion for selected company                 AuthorizationResult authorizationResult = sage50Session.RequestAccess(myCompanyIdentifier); //here we got Granted (in IIS7 and IIS Express)                 //open Company                 Sage50.Company = sage50Session.Open(myCompanyIdentifier); //this works on IIS Express, but got a"Unknow validation problem" on IIS7