Need help with non-greedy regular expression

I want help defining a rx pattern that only picks one single Invoice-tag from the example source below using the exact InvoiceNo. I have tried using "<Invoice>.*?<InvoiceNo>456<\/InvoiceNo>.*?</Invoice>" to match the middle one, but it returns everything from the start <Invoice>. How can I make this pattern non-greedy? I thought the "?" would do this. The pattern must work in .Net. Please add an appropriate comment to your bid that shows you are not a bot. ============================================= Code to base the pattern on: <?xml version="1.0" encoding="utf-8"?> <root> <Invoice> <InvoiceNo>123</InvoiceNo> <Details>abc</Details> </Invoice> <Invoice> <InvoiceNo>456</InvoiceNo> <Details>def</Details> </Invoice> <Invoice> <InvoiceNo>789</InvoiceNo> <Details>ghi</Details> </Invoice> </root>