c# - IIS combined with WatiN system.nullreferenceexception -

so im having bit off problem, when creating new instance off firefox watin.

some info might find important!

1. i able run code on iis exspress, , in winform.

2. .net trust level on full(internal) admin credentials.

3. i set references copy local = true (i did after exeption started taking place)

the error happens here:

  public string msg(string username, string password, string msg, string group, list<string> id, bool test)     {         using (firefox _ff = new firefox())//nullreferenceexception         {            lot of code         }     } 

this calls msg:

  else if (radiobutton1.checked)            {                msgbot.setapartmentstate(apartmentstate.sta);                msgbot.start();                msgbot.join();            }            blocker = true;            }            server.transfer("done.aspx", true);        }        protected void sendmsgtobot()        {         msger.msg("username", "password", textbox1.text , "159347", ids , false);     }