主题：合并电子表格数据查询是否重复问题

导入数据报错？请大家帮忙看看

Dim dlg As New OpenFileDialog '定义一个新的OpenFileDialog
dlg.Filter= "Excel文件|*.xls" '设置筛选器
If dlg.ShowDialog = DialogResult.Ok Then '如果用户单击了确定按钮
    Dim Book As New XLS.Book(dlg.FileName)
    Dim Sheet As XLS.Sheet = Book.Sheets(0)
    For i As Integer = 0 To Sheet.Cols.Count -1
        If CurrentTable.Cols.Contains( Sheet(0,i).Value) = False Then
            MessageBox.Show("目标文件不含【" & Sheet(0,i).Value & "】列,请修改与目标文件一致!", "导入错误提示")
            Return
        End If
    Next
   
    For r As Integer = 1 To Sheet.Rows.Count - 1
        Dim Filter1 As String
        For c As Integer = 0 To Sheet.Cols.Count - 1
            If c > 0 Then
                Filter1 = Filter1 & " And "
            End If
            Filter1 = Filter1 & sheet(0,c).Value & " = '" & sheet(r,c).Value & "'"    
        Next
        If DataTables("一年级毕业成绩").Find(Filter1) Is Nothing Then   ‘问题就是这句判断
            Dim dr As Row = CurrentTable.AddNew()
            For c As Integer = 0 To Sheet.Cols.Count - 1
                dr(Sheet(0,c).Value) = Sheet(r,c).Value
            Next
        End If
    Next
End If