试试改成这样

Dim text_shuru As WinForm.TextBox = e.Form.Controls("text_saomiao")
If e.Keycode=13 AndAlso text_shuru.text <> Nothing Then
    Dim fdr As DataRow = DataTables("扫描临时表").find("二维码字符串=\'" & text_shuru.text & "\'", "录入时间 DESC")
    If fdr IsNot Nothing Then
        Dim shijiancha As TimeSpan
        Dim kaishijianjian As Date=fdr("录入时间")
        shijiancha = Date.Now - kaishijianjian
        If shijiancha.TotalSeconds < 10 Then \'如果这段不执行的话就不会报错!
            MessageBox.Show("为了防止重复录入,同一个二维码的扫描时间必须大于10秒")
            Return
        End If
    End If
    Dim nr As Row = Tables("扫描临时表").AddNew
    nr("二维码字符串")= text_shuru.text
    nr("录入时间")=Date.Now
    Dim Values() As String
    values=text_shuru.text.Split(" ")
    If values.Length<>6 Then
        MessageBox.Show("您扫描的二维码是未知的,请核对后再试")
    Else
        Dim cmd As new SQLCommand
        cmd.ConnectionName = "数据源"
        cmd.CommandText="查询语句省略..."
        Dim shangpingdangan As String = cmd.ExecuteScalar
        With Tables("采购到货")
            .AddNew()
            .Current("存货编码")=values(0)
            .Current("采购单号")=values(1)
            .Current("供应商代码")=values(2)
            .Current("生产周期")=values(3)
            .Current("生产批次")=values(4)
            .Current("数量")=values(5)
            .Current("扫描时间")=Date.Now
            .Current("存货名称")=shangpingdangan
            .Current("已入ERP")=0
            .DataTable.Save
        End With
        text_shuru.Value=Nothing
    End If
End If