You would think that the Regular Expression option:
RegexOptions.Multiline
Matches input over multipline lines but if you have tried it you will know that it does not!
Use RegexOptions.Singleline instead of RegexOptions.Multiline allowing (.) to match newlines. Multi-line mode only affects anchors, and single-line mode only affects the dot.
See http://stackoverflow.com/questions/289440/cannot-get-regular-expression-work-correctly-with-multiline for more.