Regular expression is treating group as a string - regex

Question

I have a regular expression that uses the matched value from another REGEX in it. But when I test the regular expression it's not capturing the second regex group. Instead it's treating the group as a string. How would I get this regex to output the group?
Private Sub CreateGraphicsFunction(sender As Object, e As EventArgs)
Dim Regex = New Regex("infoEntityIdent=""(ICN.+?)[""].*?[>]")
Dim ICNFiles = Directory.EnumerateFiles(MoveToPath, "*.*", SearchOption.AllDirectories)
For Each tFile In ICNFiles
Dim input = File.ReadAllText(tFile)
Dim match = Regex.Match(input)
If match.Success Then
GraphicList.Add(match.Groups(1).Value)
Dim Regex2 = New Regex("<!ENTITY " & match.Groups(1).Value & " SYSTEM ""(ICN.+?[.]\w.+?)[""]")
Debug.Write(Regex2) ' outputs !ENTITY ICN-GAASIB0-00-051105-A-0YJB5-00005-A-001-01 SYSTEM "(ICN.+?[.]\w.+)["]
Dim sysFileMatch = Regex2.Match(input)
If sysFileMatch.Success Then
ICNList.Add(sysFileMatch.Groups(1).Value)
Debug.Write("found ICN " & sysFileMatch.Groups(1).Value)
End If
End If
Next
End Sub
Examples
the first Regex captures the ICN number. E.g
Using this regex captures the ICN number.
New Regex("infoEntityIdent=""(ICN.+?)[""].*?[>]")
From there I want to use the value captured in the group to go through the file again and find the matching ICN with ext. E.g
So I use the captured group from the first regex in the new regex to get the ICN number with extension.
New Regex("<!ENTITY " & match.Groups(1).Value & " SYSTEM ""(ICN.+?[.]\w.+?)[""]")
When I test this Regex out put it gives me
!ENTITY ICN-GAASIB0-00-051105-A-0YJB5-00005-A-001-01 SYSTEM "(ICN.+?[.]\w.+)["]
It's ignoring the second Regex grouping and instead treating it like part of the string instead of being used as a group. What I want is the ICN number with extension after SYSTEM
Lastest Code sample to try to get it to work
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim Files = Directory.EnumerateFiles(MovePath, "*.*", SearchOption.AllDirectories)
For Each tFile In Files
Dim input = File.ReadAllText(tFile)
Dim strREGEX = New Regex("(?=[\S\s]*?infoEntityIdent\s*=\s*""\s*(ICN[\S\s]+?)\s*""[\S\s]*?>)[\S\s]*?<!ENTITY\s+\1\s+SYSTEM\s+""\s*(ICN[\S\s]+?\.\w[\S\s]+?)\s*")
Dim match = strREGEX.Match(tFile)
If match.Success Then
Debug.Write(match.Groups(2).Value)
Else
Debug.Write(match.Groups(2).Value & " was not found")
End If
Next
End Sub

Answer 1

Combine both regex into a single regex.
This avoids the hassle of human intervention error.
This is both your actual regex combined into a single regex.
I've adjusted it so it's a good regex now.
If it doesn't match, I have no way of checking it, you've never
posted a target string.
Raw: (?=[\S\s]*?infoEntityIdent\s*=\s*"\s*(ICN[\S\s]+?)\s*"[\S\s]*?>)[\S\s]*?<!ENTITY\s+\1\s+SYSTEM\s+"\s*(ICN[\S\s]+?\.\w[\S\s]+?)\s*"
Stringed: #"(?=[\S\s]*?infoEntityIdent\s*=\s*""\s*(ICN[\S\s]+?)\s*""[\S\s]*?>)[\S\s]*?<!ENTITY\s+\1\s+SYSTEM\s+""\s*(ICN[\S\s]+?\.\w[\S\s]+?)\s*"""
Formatted and Explained:
(?= # Look ahead to find the ID ICN
[\S\s]*?
infoEntityIdent \s* = \s*
"
\s*
( ICN [\S\s]+? ) # (1), Entity IDent ICN
\s*
"
[\S\s]*? >
)
# Consume now:
[\S\s]*? # Find the ID ICN inside an ENTITY
<!ENTITY \s+
\1 # Back reference to Entity IDent ICN
\s+ SYSTEM \s+
"
\s*
( # (2 start), Some other ICN junk
ICN
[\S\s]+?
\.
\w
[\S\s]+?
) # (2 end)
\s*
"

Answer 2

You are most likely going to want to "escape" your "unknown" result from your first search to be able to use it in your new regular expression.
Something like:
Dim EscapedSearchValue As String = Regex.Escape(match.Groups(1).Value)
Dim Regex2 = New Regex("<!ENTITY " & EscapedSearchValue & " SYSTEM ""(ICN.+?[.]\w.+?)[""]")
See Regex.Escape(String) Method