How to clear unwanted characters from COM buffer

I am suppose to be getting back in my COM Buffer the word " LH FLUSH" however along with the LH FLUSH I get the following "UU LH FLUSH" or "UU LH FL?SH" I clear my InBuffer however I still get the result above. My code is below:

            serialPort.BaudRate = "9600"
            serialPort.PortName = "COM" & activeport
            serialPort.Parity = IO.Ports.Parity.None
            serialPort.DataBits = 8
            serialPort.StopBits = 1
            serialPort.RtsEnable = True
            serialPort.Open()


 serialPort.Write("<@:L" & tempArray(0) & Total_Bytes & "<" & UpdatePoint & "," & "0" & Int_Rank & "," & GageDescription & "," & USL & "," & LSL & ">")
                    System.Threading.Thread.Sleep(100)
                    serialresponse1 = serialPort.ReadExisting


What Am I doing Wrong?