.txt filename iteration vb.net - regex

Question

I've got a little problem with regards to iterating the filename of the txt files. I've got a filename format that goes like this: <date>-<year>_filename-<number>.txt. The problem is that when <number> reaches 9, the filename stops iterating.
The filenames goes like this:
31-2014_filename-1
31-2014_filename-2
31-2014_filename-3
31-2014_filename-4
31-2014_filename-5
31-2014_filename-6
31-2014_filename-7
31-2014_filename-8
31-2014_filename-9
31-2014_filename-10
The function only detects up to 9. Anything beyond that number is ignored.
Below is the code
Dim lastreport As Integer = 1
Public Sub GetLastNo(ByVal filePath As String)
Dim lastFile As String = 1
Dim files() As String = Directory.GetFiles(filePath, "*.txt")
For Each File As String In files
File = Path.GetFileNameWithoutExtension(File)
Dim numbers As MatchCollection = Regex.Matches(File, "(?<num>[\d]+)")
For Each number In numbers
number = CInt(number.ToString())
If number > 0 And number < 1000 And number > lastFile Then
lastFile = number
End If
lastreport = number
Next
Next
End Sub

Answer 1

Here it is:
(?<num>\d+(?=$))
This would make sure that the digits are followed by a > and $(End of line). This would make sure that it is the last set of digits.

Answer 2

It would really help to see some real filenames, including some that fail to match (your description is not completely unambiguous: for example what is <date> if it does not include the year?).
But assuming files like:
30May-2014_Stuff-1.txt
30May-2014_Stuff-3.txt
30May-2014_Stuff-5.txt
30May-2014_Stuff-7.txt
30May-2014_Stuff-9.txt
30May-2014_Stuff-11.txt
then using the .NET regex engine (from PowerShell (PSH) here as quicker to test with):
(?<num>\d+)$
should match the final digits ($ matches the end of the string) of the filename without extension: BaseName in PSH):
dir | foreach { if ($_.BaseName -match '(?<num>\d+)$') { $matches['num'] } }
gives:
1
11
3
5
7
9
So all filenames are matched, and the final number of their basenames is matched by group "num" of the regex.
I think there is something else going on in your approach: I would suggest changing to only get a single match per filename (and use Regex.Match rather than Matches to be consistent).