guys..i got a lilttle problem with my code,can anyone help

Question

 Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
 Dim myconnection As New SqlConnection

        myconnection.ConnectionString = "Data Source=USER-PC;Initial Catalog=MiSInventory;Integrated Security=True"

        Dim READER As SqlDataReader

      

        Try

            myconnection.Open()

            Dim Query As String

    

            Query = "SELECT COUNT(DISTINCT Category)AS NumCount FROM ItemAdd GROUP BY Category"

            READER = Command.ExecuteReader

            Command = New SqlCommand(Query, myconnection)

            nDataAdapter = New SqlDataAdapter(Command)

            ds = New DataSet()

            nDataAdapter.Fill(ds)

            TextBox1.Text = "ds.Tables[0].Rows[1][NumCount].ToString()"

            MessageBox.Show("Data will be count")

            myconnection.Close()

 Catch ex As Exception

            MessageBox.Show("Could not connect database:  " & ex.Message, "Database Connection Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

        Finally

            myconnection.Dispose()

        End Try

    End Sub

When i click the button count it says "object reference not set to an instance of an object"