Error in saving the data

Additional information: Violation of PRIMARY KEY constraint 'PK__tblPayme__A17005CC944C102D'. Cannot insert duplicate key in object 'dbo.tblPayment'. The duplicate key value is (1).

<pre>Imports System.Data.SqlClient
Imports System.Data

Public Class Payment
    Dim conn As New SqlConnection
    Dim cmd As SqlCommand
    Dim da As SqlDataAdapter
    Dim strcon As String = "Server=DESKTOP-C6IEOUN\SQLEXPRESS;database =NEWCMO; integrated security=True;"
    Private Sub dtpDateToday_ValueChanged(sender As Object, e As EventArgs) Handles dtpDateToday.ValueChanged

    End Sub

    Private Sub Payment_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Private Sub btnCompute_Click(sender As Object, e As EventArgs) Handles btnCompute.Click
        txtBal.Text = Val(txtAmt.Text) - Val(txtPayment.Text)
    End Sub

    Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
        Dim cmd As New SqlCommand
        conn.ConnectionString = strcon
        conn.Open()
        cmd.Connection = conn
        cmd.CommandText = "INSERT INTO tblPayment (patientID,Surname,Firstname,Age,[Total Amount to be Paid],[Type of Payment],Payment,Balance) VALUES(@PID,@SN,@FN,@Age,@Amt,@TypePayment,@Payment,@Balance)"

        cmd.Parameters.AddWithValue("@PID", txtPID.Text)
        cmd.Parameters.AddWithValue("@SN", txtSN.Text)
        cmd.Parameters.AddWithValue("@FN", txtFN.Text)
        cmd.Parameters.AddWithValue("@Age", txtAge.Text)
        cmd.Parameters.AddWithValue("@Amt", txtAmt.Text)
        cmd.Parameters.AddWithValue("@TypePayment", cmbTypeOfPayment.Text)
        cmd.Parameters.AddWithValue("@Payment", txtPayment.Text)
        cmd.Parameters.AddWithValue("@Balance", txtBal.Text)

        cmd.ExecuteNonQuery()
        MessageBox.Show("Successful Added Data")
        conn.Dispose()
        conn.Close()
    End Sub

    Private Sub Payment_Click(sender As Object, e As EventArgs) Handles Me.Click
        ''''''''''''''''Searching''''''''''''''''''''''''''

        Dim connection As New SqlConnection("Server=DESKTOP-C6IEOUN\SQLEXPRESS;database =NEWCMO; integrated security=True;")
        Dim command As New SqlCommand("Select * From tblRegPatient where patientID =@PID", connection)

        ' command.Parameters.Add("@PID", SqlDbType.Int).Value = txtPID.Text
        command.Parameters.AddWithValue("@PID", txtPID.Text)
        Dim adapter As New SqlDataAdapter(command)
        Dim table As New DataTable()
        adapter.Fill(table)
        If table.Rows.Count() > 0 Then

            txtSN.Text = table.Rows(0)(1).ToString()
            txtFN.Text = table.Rows(0)(2).ToString()
            txtAge.Text = table.Rows(0)(7).ToString()

        Else
            MsgBox("No Data Found", vbInformation, "Not Found")
        End If
    End Sub
End Class