อันนี้เปนหน้าโปรแกรมครับ  คือต้องการคำนวณ


แต่ไม่สามารถคำนวณได้  แจ้งตามภาพอ่ะครับ เพราะอะไรหรอครับ


โค้ด
Imports System.Data.OleDb
Imports System.Data
Public Class DBConnect
    '  Public dbName As String
    Public Tbl As DataTable
    Public ObjConn As OleDbConnection
    Private StrConn As String
    Private Cmd As OleDbCommand
    Public Sub OpenConn()
        If ObjConn.State = ConnectionState.Open Then ObjConn.Close()
        ObjConn.Open()
    End Sub
    Public Sub Runcmd(ByVal xStr As String)
        Cmd = New OleDbCommand
        Call OpenConn()
        Cmd.CommandType = CommandType.Text
        Cmd.CommandText = xStr
        Cmd.Connection = ObjConn
        Cmd.ExecuteNonQuery()
        Cmd = Nothing
        Application.DoEvents()
        ObjConn.Close()
    End Sub
    Public Sub Runsql(ByVal xStr As String)
        Cmd = New OleDbCommand
        Call OpenConn()
        Cmd.CommandType = CommandType.Text
        Cmd.CommandText = xStr
        Cmd.Connection = ObjConn
        Cmd.ExecuteNonQuery()
        Cmd = Nothing
        Application.DoEvents()
        ObjConn.Close()
    End Sub
    Public Sub View(ByVal xStr As String)
        Dim Da As OleDbDataAdapter
        Call OpenConn()
        Da = New OleDbDataAdapter(xStr, ObjConn)
        Tbl = New DataTable()
        Da.Fill(Tbl)
        Da = Nothing
        ObjConn.Close()

    End Sub