Regular Expression only returns 1 match - regex

Question

My VBA function should take a string referencing a range of units (i.e. "WWW1-5") and then return another string.
I want to take the argument, and put it in a comma separated string,
So "WWW1-5" should become "WWW1, WWW2, WWW3, WWW4, WWW5".
It's not always going to be a single digit. For example, I might need to separate "XXX11-18" or something similar.
I have never used regular expressions, but keep trying different things to make this work and it seems to only be finding 1 match instead of 3.
Any ideas? Here is my code:
Private Function split_group(ByVal group As String) As String
Dim re As Object
Dim matches As Object
Dim result As String
Dim prefix As String
Dim startVar As Integer
Dim endVar As Integer
Dim i As Integer
Set re = CreateObject("vbscript.regexp")
re.Pattern = "([A-Z]+)(\d+)[-](\d+)"
re.IgnoreCase = False
Set matches = re.Execute(group)
Debug.Print matches.Count
If matches.Count <> 0 Then
prefix = matches.Item(0)
startVar = CInt(matches.Item(1)) 'error occurs here
endVar = CInt(matches.Item(2))
result = ""
For i = startVar To endVar - 1
result = result & prefix & i & ","
Next i
split_group = result & prefix & endVar
Else
MsgBox "There is an error with splitting a group."
split_group = "ERROR"
End If
End Function
I tried setting global = true but I realized that wasn't the problem. The error actually occurs on the line with the comment but I assume it's because there was only 1 match.
I tried googling it but everyone's situation seemed to be a little different than mine and since this is my first time using RE I don't think I understand the patterns enough to see if maybe that was the problem.
Thanks!

Answer 1

Try the modified Function below:
Private Function split_metergroup(ByVal group As String) As String
Dim re As Object
Dim matches As Variant
Dim result As String
Dim prefix As String
Dim startVar As Integer
Dim endVar As Integer
Dim i As Integer
Set re = CreateObject("VBScript.RegExp")
With re
.Global = True
.IgnoreCase = True
.Pattern = "[0-9]{1,20}" '<-- Modified the Pattern
End With
Set matches = re.Execute(group)
If matches.Count > 0 Then
startVar = CInt(matches.Item(0)) ' <-- modified
endVar = CInt(matches.Item(1)) ' <-- modified
prefix = Left(group, InStr(group, startVar) - 1) ' <-- modified
result = ""
For i = startVar To endVar - 1
result = result & prefix & i & ","
Next i
split_metergroup = result & prefix & endVar
Else
MsgBox "There is an error with splitting a meter group."
split_metergroup = "ERROR"
End If
End Function
The Sub I've tested it with:
Option Explicit
Sub TestRegEx()
Dim Res As String
Res = split_metergroup("DEV11-18")
Debug.Print Res
End Sub
Result I got in the immediate window:
DEV11,DEV12,DEV13,DEV14,DEV15,DEV16,DEV17,DEV18

Answer 2

Another RegExp option, this one uses SubMatches:
Test
Sub TestRegEx()
Dim StrTst As String
MsgBox WallIndside("WAL7-21")
End Sub
Code
Function WallIndside(StrIn As String) As String
Dim objRegex As Object
Dim objRegMC As Object
Dim lngCnt As Long
Set objRegex = CreateObject("VBScript.RegExp")
With objRegex
.Global = True
.IgnoreCase = True
.Pattern = "([a-z]+)(\d+)-(\d+)"
If .test(StrIn) Then
Set objRegMC = .Execute(StrIn)
For lngCnt = objRegMC(0).submatches(1) To objRegMC(0).submatches(2)
WallIndside = WallIndside & (objRegMC(0).submatches(0) & lngCnt & ", ")
Next
WallIndside = Left$(WallIndside, Len(WallIndside) - 2)
Else
WallIndside = "no match"
End If
End With
End Function

Answer 3

#Shai Rado 's answer worked. But I figured out on my own WHY my original code was not working, and was able to lightly modify it.
The pattern was finding only 1 match because it was finding 1 FULL MATCH. The full match was the entire string. The submatches were really what I was trying to get.
And this is what I modified to make the original code work (asking for each submatch of the 1 full match):