Varriable array size

[Nigorr]

I have the following code, and what it is doing is going through a spreadsheet in excel and splitting up the string that is dumped out of Novell. What it does is for example it splits "username.context.tree" into three parts. This works fine except when it comes to things like "username.subcontext.context.tree" or "username.tree". So how would i go about making choices and giving me the right bits in the places??

Option Explicit
Function mySplit(strToSplt, strSplitOn) 'Split Function
    Dim ip1, ip2
    Dim strArray()
    Dim iCount
    
    
    ip1 = 1: ip2 = 1
    Do
      ip2 = InStr(ip1, strToSplt, strSplitOn)
      If ip2 = 0 Then
        ip2 = Len(strToSplt) + 1
      End If
      
      If iCount Mod 100 = 0 Then
        ReDim Preserve strArray(iCount + 100)
      End If
      strArray(iCount) = Mid$(strToSplt, ip1, ip2 - ip1)
      
      ip1 = ip2 + Len(strSplitOn)
      iCount = iCount + 1
      
    Loop Until ip2 >= Len(strToSplt)
    
    ReDim Preserve strArray(iCount - 1)
    mySplit = strArray
    
End Function
 
Sub test()
Dim rw
Dim intRow As Long
Dim Mystr, strParams, strUserName, strContext, strSubContext, strTree As String
 
intRow = 1
For Each rw In Worksheets("allusers").Cells(1, 1).CurrentRegion.Rows 'Do this for every row in excel
    intRow = intRow 'get the row number (Im not really sure how this works but it does further down
    Mystr = rw.Cells(1, 1).Value 'Get the string to split up
    strParams = mySplit(Mystr, ".") 'Send string tho be split
    If isArray(strParams) Then 'assign the split string to the right variables
        strUserName = Trim(strParams(0))
        strSubContext = Trim(strParams(1))
        strContext = Trim(strParams(2))
        strTree = Trim(strParams(3))
    End If
    rw.Range("C" & intRow).Value = strUserName 'put the username in cell D and the row
    rw.Range("D" & intRow).Value = strSubContext 'put the context1 if it exsits in cell D and the row
    rw.Range("E" & intRow).Value = strContext 'put the context 2 in cell D and the row
    rw.Range("F" & intRow).Value = strTree 'put the tree in cell E and the row
 
Next rw
 
End Sub

Hope you see what I am getting at..