$.ajax({
    url: "test.aspx/Start",
    datatype: "json",
    cache: false,
    async: true,
    contentType: "application/json; charset=utf-8",
    method: "POST",
    data: JSON.stringify({ "HTMLString": str }),
    success: function (data) {
        if (data.d.length > 0) {
            ShowMessage(data.d, "error");
        }
    }

}); return false;

[System.Web.Services.WebMethod]
    [System.Web.Script.Services.ScriptMethod(ResponseFormat = System.Web.Script.Services.ResponseFormat.Json)]
    public static string Start(string HTMLString)
    {
        bool IsInstalled = Handlers.CheckDirectumIsInstalled();
        string result = "";
        if (IsInstalled)
        {
            string filePath = Path.GetTempPath() + "\" + fileName;
            // Создадим документ в темп пользователя
            Handlers.ConvertToPDF(html, filePath, true);

            // Подключаемся к СЭД
            string AppProgId = "SBLogon.LoginPoint";
            Type LoginPointType = Type.GetTypeFromProgID(AppProgId);
            dynamic LoginPoint = Activator.CreateInstance(LoginPointType);
            dynamic App = LoginPoint.GetApplication("ServerName=STEST;
                                                        DBName=DBTEST;
                                                      UserName=;Password=");
            dynamic Src = App.ScriptFactory.GetObjectByName("test");
            Src.Params.SetVar("document", filePath);
            Src.Execute();
        }
        else
        {
            result = "не установлено ПО...";
        }


        return result;

    }

ExceptionType: "System.Runtime.InteropServices.COMException"
Message: "Вход в систему не произведен"
StackTrace:"   at System.Dynamic.ComRuntimeHelpers.CheckThrowException(Int32
hresult, ExcepInfo& excepInfo, UInt32 argErr, String message)
↵   at CallSite.Target(Closure , CallSite , ComObject , String )
↵   at CallSite.Target(Closure , CallSite , Object , String )
↵   at SpecodInfo.Test.Start(String HTMLString)

dynamic App = LoginPoint.GetApplication("ServerName=STEST;
                                            DBName=DBTEST;
                                          UserName=;Password=");