工作7000次后，sheets.add突然开始给出错误1004

Question

我的代码应该打开数据的文本文件，从中记录某些值，记录它们，关闭它，然后打开下一个文件。到目前为止，每年每天每小时都有一个文件，为了跟踪这些工作表，我一直在重命名它们。

我在5月底遇到错误1004＆＃34;方法＆＃39;添加＆＃39;对象＆＃39;表格＆＃39;失败＆＃34;，即使它已经工作了大约7000次。

有问题的一行是：

Sheets.Add(Before:=Sheets(1)).Name = lm & " " & j & " Hour " & kk

这里可能出现什么问题？我是VBA的新手，所以它可能很容易成为我忽略的东西，但为什么只是现在它才会被淘汰？

（最后一个半相关的说明：刚刚报名参加专门问这个问题;如果我发布了任何不正确或格式错误，我道歉！）

编辑：如果它有帮助，那么该代码的代码是：

For i = 1 To 12                                     'for all months
  For j = 1 To 31                                 'for all days
    For k = 0 To 23                             'for all hours
      Select Case i
        Case "1"
          mmm = "Jan"
          lm = "January"
        Case "2"
          mmm = "Feb"
          lm = "February"
        Case "3"
          mmm = "Mar"
          lm = "March"
        Case "4"
          mmm = "Apr"
          lm = "April"
        Case "5"
          mmm = "May"
          lm = "May"
        Case "6"
          mmm = "Jun"
          lm = "June"
        Case "7"
          mmm = "Jul"
          lm = "July"
        Case "8"
          mmm = "Aug"
          lm = "August"
        Case "9"
          mmm = "Sep"
          lm = "September"
        Case "10"
          mmm = "Oct"
          lm = "October"
        Case "11"
          mmm = "Nov"
          lm = "November"
        Case "12"
          mmm = "Dec"
          lm = "December"
      End Select

      If i < 10 Then
        ii = "0" & i
      Else
        ii = i
      End If
      If j < 10 Then
        jj = "0" & j
      Else
        jj = j
      End If
      If k < 10 Then
        kk = "0" & k
      Else
        kk = k
      End If

      Sheets.Add(Before:=Sheets(1)).Name = lm & " " & j & " Hour " & kk

 'the code after this just opens up the text file at a path determined by 
 'the month, day, and hour, sorts data.  then comes: 

      Sheets(1).Delete
    Next k
  Next j
Next i