dim sStr as string=","trydim dt as datatable =getData(1)If dt.Rows.Count > 0 Then Dim drRows() As DataRow = dt.Select("F1 like 'BCX/%' ")  If drRows.Length > 0 Then     Dim i As Integer     For i = 0 To drRows.Length - 1         sStr += DBNULL2Str(drRows(i).Item("F1") + ","     Next End IfEnd IfCatch ex As Exception   log(ex) end Try以上運(yùn)行時(shí)，偶爾會(huì)出現(xiàn)log “System.NullReferenceException: 未將對象引用設(shè)置到對象的實(shí)例”錯(cuò)誤 代碼竟然是這行： sStr += DBNULL2Str(drRows(i).Item("F1") + ","由于調(diào)試正常，批量客戶運(yùn)行時(shí)，會(huì)這樣，無法調(diào)試。請問有什么可能？