VB Split语句下标越界

VB Split语句下标越界，以下是代码

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Dim AreaName() As String

Private Sub Combo1_Click()
Combo2.Clear
Dim A
A = Split(Split(AreaName(Combo1.ListIndex), ":")(1), ",")
For I = 0 To UBound(A)
Combo2.AddItem A(I)
Next
End Sub

Private Sub Form_Load()
Dim s As String, I As Integer
Open "C:\1.txt" For Input As #1
I = 0
Combo1.Clear
While Not EOF(1)
Line Input #1, s
If UBound(Split(s, ":")) > 0 Then
ReDim Preserve AreaName(I) As String
AreaName(I) = s
Combo1.AddItem Split(s, ":")(0)
I = I + 1
End If
Wend
Close #1

Open "C:\规定.txt" For Input As #3
I = 0
Combo3.Clear
While Not EOF(3)
Line Input #3, s
If UBound(Split(s, ":")) > 0 Then
ReDim Preserve AreaName(I) As String
AreaName(I) = s
Combo3.AddItem Split(s, ":")(0)
I = I + 1
End If
Wend
Close #3
End Sub

TXT1内容：123:A,B,C

由于我要同时加载COMBO1和COMBO3甚至更多按键，同时要COMBO2能显示A,B,C内容，但是运行时VB给出错误提示是这句：
A = Split(Split(AreaName(Combo1.ListIndex), ":")(1), ",")下标越界，这个要怎么弄？

AA=Split(AreaName(Combo1.ListIndex), ":")
if ubound(AA)>0 then A = Split(AA(1), ",")

下标越界说明request.form("town")获得的值少于2个 <% city = request.form("city") town = request.form("town") if town = "" then iii1 = split(city,",") else iii1 = split(town,",") end if for jjj = 0 to ubound(iii1) response.write iii1(jjj) & " " next %> 看看这样可以不？ town和city都是要 aaa,bbb,ccc,ddd这样的值