Measure temperature with a Keithley 2700 and 7700 multiplexer in C#

I am trying to figure out the proper syntax to get the Keithley multimeter to return the temperature from channel 1 on the first slot (@101). I am connected to the Keithley 2700 through a USB to Serial connection. I can query the DMM for the serial number. So I know I am connected and can send commands. But I don't understand how to format the command to measure the temperature (or any of the resistances, for that matter).

   public string GetTemperature(string comPort)
   {
       string msg = "MEAS:TEMP?:@101"; // I also tried "*TEMP? @101"
       string response = string.Empty;
       SerialPort sp = new SerialPort();
       sp.PortName = comPort;
       if (!sp.IsOpen)
           sp.Open();
       while (sp.BytesToRead > 0)
       {
           response += sp.ReadExisting();
       }
       sp.DiscardInBuffer();
       sp.Close();
       return response;
   }

I get no errors. It just returns an empty string. 
Can anyone help?

Thanks.