FlexUnit 4, Flash Builder 4, and Flex SDK 4

I am endeavouring to create a project using these in combination. When I created my test runner under SDK 4, it would fail while trying to initialise the test. I decided to build FlexUnit 4 with SDK 4 but it doesn't seem to find the mx name space.

Is there a version of FlexUnit 4 built for SDk 4? If not is there some rules for the conversion of a project so it can be built under SDK 4.

I know Flash Builder 4 will build FlexUnit and rune the FlexUnit TuirnKey tests if I leave it using SDK 3.2 but I am keen to get on with learning and using SDK 4.