permutation not accepting large words - vb.net

Question

the vb.net code below permutates a given word...the problem i have is that it does not accept larger words like "photosynthesis", "Calendar", etc but accepts smaller words like "book", "land", etc ...what is missing...Pls help
Module Module1
Sub Main()
Dim strInputString As String = String.Empty
Dim lstPermutations As List(Of String)
'Loop until exit character is read
While strInputString <> "x"
Console.Write("Please enter a string or x to exit: ")
strInputString = Console.ReadLine()
If strInputString = "x" Then
Continue While
End If
'Create a new list and append all possible permutations to it.
lstPermutations = New List(Of String)
Append(strInputString, lstPermutations)
'Sort and display list+stats
lstPermutations.Sort()
For Each strPermutation As String In lstPermutations
Console.WriteLine("Permutation: " + strPermutation)
Next
Console.WriteLine("Total: " + lstPermutations.Count.ToString)
Console.WriteLine("")
End While
End Sub
Public Sub Append(ByVal pString As String, ByRef pList As List(Of String))
Dim strInsertValue As String
Dim strBase As String
Dim strComposed As String
'Add the base string to the list if it doesn't exist
If pList.Contains(pString) = False Then
pList.Add(pString)
End If
'Iterate through every possible set of characters
For intLoop As Integer = 1 To pString.Length - 1
'we need to slide and call an interative function.
For intInnerLoop As Integer = 0 To pString.Length - intLoop
'Get a base insert value, example (a,ab,abc)
strInsertValue = pString.Substring(intInnerLoop, intLoop)
'Remove the base insert value from the string eg (bcd,cd,d)
strBase = pString.Remove(intInnerLoop, intLoop)
'insert the value from the string into spot and check
For intCharLoop As Integer = 0 To strBase.Length - 1
strComposed = strBase.Insert(intCharLoop, strInsertValue)
If pList.Contains(strComposed) = False Then
pList.Add(strComposed)
'Call the same function to review any sub-permutations.
Append(strComposed, pList)
End If
Next
Next
Next
End Sub
End Module

Answer 1

Without actually creating a project to run this code, nor knowing how it 'doesn't accept' long words, my answer would be that there are a lot of permutations for long words and your program is just taking much longer than you're expecting to run. So you probably think it has crashed.
UPDATE:
The problem is the recursion, it's blowing up the stack. You'll have to rewrite your code to use an iteration instead of recursion. Generally explained here
http://www.refactoring.com/catalog/replaceRecursionWithIteration.html
Psuedo code here uses iteration instead of recursion
Generate list of all possible permutations of a string