The type initializer for 'Component.PersonDAL' threw an exception.

Hi all,
The type initializer for 'Component.PersonDAL' threw an exception. this error in service form and
System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.TypeInitializationException: The type initializer for 'Component.PersonDAL' threw an exception. ---> System.NullReferenceException: Object reference not set to an instance of an object.
  at Component.PersonDAL..cctor() in C:\Users\aasra\Documents\Visual Studio 2010\Projects\Service\Services\Component\PersonDAL.cs:line 20
  --- End of inner exception stack trace --- error in application form

thanking you
  at Component.PersonDAL.SavePerson(Person per)
  at Services.Service.Save(Person per) in C:\Users\aasra\Documents\Visual Studio 2010\Projects\Service\Services\Services\Service.asmx.cs:line 25
  --- E ...