Wade,
Sure, that normally indicates that you have an error in the code Check your problems window and run a "clean" from the project menu.
Wade,
Well you just completely exited my comfort zone. I have never used mxmlc to compile anything. That's what I have Flash Builder for. All I do know from reading the forums for many years now is that people struggle to get Flex Viewer widgets to compile if they are using anything other than Flex or Flash Builder.