Did you include the asterisk? 
*@dbensoncontrols.co.uk
The following function in the same module will give you the folder path (if it exists) from the five input characters
thus 
fPath = GetPath
Private Function GetPath() As String
Const strRoot As String = "\\Servername\Private\Projects\Drawings\customer\"
Dim FSO As Object
Dim Folder As Object
Dim subFolder As Object
Dim strPath As String
Dim bPath As Boolean
Start:
    strPath = InputBox("Enter the 5 character project number.")
    If strPath = "" Then GoTo lbl_Exit
    If Not Len(strPath) = 5 And Not IsNumeric(Right(strPath, 4)) Then
        MsgBox "Enter a Letter and 4 digits!"
        GoTo Start:
    End If
    Set FSO = CreateObject("Scripting.FileSystemObject")
    Set Folder = FSO.GetFolder(strRoot)
    For Each subFolder In Folder.SubFolders
        'Debug.Print subFolder & vbTab & strRoot & strPath
        If InStr(1, CStr(subFolder), UCase(strPath)) > 0 Then
            strPath = CStr(subFolder) & Chr(92)
            bPath = True
            Exit For
        End If
    Next
    If Not bPath Then strPath = ""
lbl_Exit:
    GetPath = strPath
    Exit Function
End Function