I am trying to display a message box if the string entered in the textbox was not found in the database

Also, if the enter button is pressed and the textbox is blank, then a msgbox should say "A value must be entered"

I have tried everything to my knowledge and vb.net does not like it.



Code:
Private Sub ButtonLookup_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonLookup.Click
        Try
            Dbconnect.Open()    ' Try Block - Connects To The Database. Displays An Error If It Can't.


            

            Dim DbAdapter As New MySqlDataAdapter("SELECT * FROM Itemlist WHERE Barcode = '" & TextBoxItemInput.Text & "'", Dbconnect)
            Dim DbDataSet As New DataSet
            DbAdapter.Fill(DbDataSet, "Itemlist")
            Dim DbTable As DataTable = DbDataSet.Tables("Itemlist")

      

                For Each row As DataRow In DbTable.Rows

                    Dim ItemSku As Integer = row("ItemSku").ToString()
                    Dim ItemName As String = row("ItemName").ToString()
                    Dim Barcode As String = row("Barcode").ToString()
                    Dim Price As Decimal = row("Price").ToString()

                    ItemGridView.Rows.Add(Barcode, ItemName, 1, Price, Price)
                    LabelStatus.Text = "Item Added"
                    LineDisplay.ClearText()
                    LineDisplay.DisplayText(ItemName & "    $" & Price)
                    ItemGridView.ClearSelection()
                    TextBoxItemInput.Clear()

             Next