how to avoid error CommandText property has not been initialized properly

[hrutu]

database is in the sqlYog, while i run this program i am getting the error CommandText property has not been initialized properly..? please help me

Imports MySql.Data.MySqlClient Imports System.Data

Partial Class login Inherits System.Web.UI.Page

Public dbconn As New MySqlConnection
Public sql As String
Public dbcomm As New MySqlCommand
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    dbconn = New MySqlConnection("data source= localhost; user id=root; password=search; database=bookstore;")
    dbconn.Open()
    dbcomm.Connection = dbconn

End Sub

Protected Sub btn_login_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn_login.Click

    Try
        dbcomm = New MySqlCommand(sql, dbconn)

        sql = "select * from bookstore.lib_user where username=@username  and password=@password"

        dbcomm.Parameters.AddWithValue("@username", txt_username.Text)
        dbcomm.Parameters.AddWithValue("@password", txt_password.Text)

        Dim dbadpt As New MySqlDataAdapter(dbcomm)
        Dim dt As New DataTable()
        dbadpt.Fill(dt)
        If dt.Rows.Count > 0 Then
            MsgBox("login is suceesfull")
        Else
            Literal1.Text = "invalid login"
        End If

    Catch ex As Exception
        MsgBox("read this error: " + ex.Message)
    End Try
End Sub
End Class

[Rabbit]

Please use code tags when posting code or formatted data.

On lines 19 and 21, you create your command with a blank variable, then you populate the variable. That's backwards.