For some reason, there is no option in the create page dialogue to select a master page. I have tried both programatically declaring the MP and by updating the property in the Properties pane. – NoCarrier 13 mins ago
I believe its because i'm using a "web application" vs a "web site" – NoCarrier 9 mins ago
Chances are it is in the <@PAGE> tag where your problem is. That said, it doesnt make a difference if you are using a Web Application or not. To create a Child Page, right click on your master page in the Solution Explorer and choose Add Content Page.