Except for the MX charting controls and the MX Spacer control, mobile applications do not support the MX component set defined in the mx.* packages.
So, when I try to compile my MX control heavy application as a Flex Mobile application, I get a stack of compilation "library not found" errors. Yet, when I try to use adt to compile the project for iOS, it compiles (and runs) just fine.
What's going on? What should I be using?
By default a Flex Mobile project in Flash Builder doesn't have mx.swc. I assume when you are compiling from outside of Flash Builder you are adding that SWC?