Imports System.Data.OleDb
Module Commonmodule
    Public mydap As OleDbDataAdapter
    Public mydataset As DataSet = New DataSet
    Public mytable As DataTable
    Public myrow As DataRow
    Public mycmdbuilder As OleDbCommandBuilder
    Public Function SQLOpera(ByVal str As String, ByVal table As String)
        Try
            Dim row As Integer = 0
            Dim selectstring As String
            selectstring = "provider=Microsoft.Jet.OLEDB.4.0;Data Source="
            selectstring = selectstring & Application.StartupPath() & "\Data\student.mdb"
            mydap = New OleDbDataAdapter(str, selectstring)
            mydataset.Clear()
            mydataset.Tables.Clear()
            mydap.Fill(mydataset, table)
            mytable = mydataset.Tables.Item(0)
            myrow = mytable.Rows.Item(row)
        Catch ex As Exception
        End Try
        Return Nothing
    End Function
End Module



各位我在模块中编了这样的代码，为什么我在其它窗口中用它会出现数据没有加载这样的窗口。难道还需要其它的设置吗？
这是什么原因，谁能帮帮忙