B4J Question Byte array to text

Sub astream_NewData (Buffer() As Byte)
    Log(BytesToString(Buffer, 0, Buffer.Length, "utf8"))
'    for testing
    Dim bc As ByteConverter
    bc.LittleEndian = True
    Dim a As String = bc.HexFromBytes(Buffer)
    Log("a = "&a&" len = "&Buffer.Length)
'   
    Dim s(4) As Byte
    bc.ArrayCopy(Buffer,6,s,0,4)
    Dim d() As Float = bc.FloatsFromBytes(s)
    Dim str As String = d(0)
    Dim dbl As Double = d(0)
    Log("d = "&d(0))
    Log("str = "&str)
    Log ("ppm = "& str.SubString2(0,5))
    Log ("dbl = "& NumberFormat(dbl,0,3))
    lblPPM.Text = str.SubString2(0,5)           - displays symbols instead of text