How to import FB 4.5 projects into FB 4.7?

I had several projects that were built in Flex and than moved to FB 4.5 and now I installed the CC pack with Flash Builder 4.7 premium.

I imported all my projects in the new Flash Builder and I even installed the SDK it used before (4.5.1) and it still show the following error and I can't compile it:

error: Unknown Flex SDK: "Flex 4.5.1"

location: Unknown

type: Flex Problem

Does anyone have any idea how should I import old projects into the new Flash Builder 4.7?

Thank you!