Trouble with InputBoxes

Here is a way to catch most outcomes of interacting with the dialog;

Dim value As String
value = InputBox("Please enter a #", "Determine Limit", 10000)

If (StrPtr(value) = 0) Then
    MsgBox "You pressed cancel or [X]"

ElseIf (value = "") Then
    MsgBox "You did not enter anything"

ElseIf (Val(value) = 0 And value <> "0") Then
    MsgBox "Invalid number"

Else
    MsgBox "You entered " & value

End If

When in doubt, check the inbuilt VBA help ;)

InputBox() returns a String

You can try this for Integers

Sub Sample()
    Dim Ret As String, userInputValue As Integer

    'Text to display, Title, Default Value
    Ret = InputBox("Please enter a #", "Determine Limit", 10000)

    If Ret = "" Then
        MsgBox ("You pressed the cancel button... or you pressed OK without entering anything")
    Else
        If IsNumeric(Ret) Then
            userInputValue = Val(Ret)
        Else
            MsgBox ("Incorrect Value")
        End If
    End If
End Sub

InputBox returns a string regardless of the number the user enters. If they click Cancel, it returns an empty string.

Try this in the Immediate window.

? TypeName(InputBox("Please enter a #", "Determine Limit", 10000))
String

For the test in your code, check whether the numerical equivalent of userInputValue is equal to zero.

If Val(userInputValue) = 0 Then
    MsgBox ("You pressed the cancel button...")
End If

Note than InputBox doesn't allow you to distinguish whether the user clicked Cancel or deleted the starting value (10000) and clicked OK. Either way, InputBox returns an empty string (""). And Val("") also returns zero. If that will be a problem, substitute a custom form to gather the user input ... which is not as limited as InputBox.