Connected DT80 with modbus ok fine VB.NET, but not reading data from DT80 registers

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VB

I an writing a program to read data from DT80 supporting Modbus RTU.My below VB. net2010 code is able to connnect DT80, but not reading register value to the form text box.
Please help me. Thanks in advance.

What I have tried:

Dim ModbusClient As EasyModbus.ModbusClient = New EasyModbus.ModbusClient(Me.TextBox1.Text, Me.TextBox2.Text)  'connecting using IP, port

Try
    ModbusClient.Connect()

    TextBox3.Text = ComError
    TextBox3.ForeColor = Color.Green
    Label4.Text = "Connected to Slave"
    Label4.ForeColor = Color.Green
    If TextBox3.Text = 0 Then
        Label4.Text = "logging......"
        Dim Regs As Integer()
        Regs = ModbusClient.ReadHoldingRegisters(4, 5)

        Me.TextBox4.Text = Regs(0)
        Me.TextBox5.Text = Regs(1)
        Me.TextBox6.Text = Regs(2)
        Me.TextBox7.Text = Regs(3)
        Me.TextBox8.Text = Regs(4)


        ModbusClient.Disconnect()

    End If


Catch ex As Exception
    TextBox3.Text = 1
    TextBox3.ForeColor = Color.Red
    Label4.Text = "Connection Error!"
    Label4.ForeColor = Color.Red
End Try