I'm trying to compile an existing Flex3 project with the Flex4 SDK. I'm getting this error:

`Warning: This compilation unit did not have a factoryClass specified in Frame metadata to load the configured runtime shared libraries. To compile without runtime shared libraries either set the -static-link-runtime-shared-libraries option to true or remove the -runtime-shared-libraries option.`

The resulting file is roughly the same as my old Flex3 compiled .swf file. Playing the resulting .swf file in the Flash Player also gives the following errors:

`An Actionscript error ocurred: VerifyError: Error #1014: Class spark.core::SpriteVisualElement could not be found`

If I set the compiler attribute `static-link-runtime-shared-libraries` to true, then the error disappears and all is well. However, the size of the resulting .SWF is a couple of 100K's bigger. And that's not what I want.

I don't fully understand the concept of runtime shared libraries, but it seems that with the option to statically link them set to true, the libraries are included in the .swf. However, I like to exclude them from the .swf and only load the needed library at runtime, as my project seemed to do with Flex3 (I didn't know that by the way).

If I understand correctly, playerglobal.swc should hold all the necessary code for the external libraries that my .swf has to load. Do Flex4 compiled files need more libraries? Should I do something with the factoryClass in the Frame metadata tag?

I think my question boils down to this: How do I compile a Flex4 .swf that is the same size as my previous Flex3 compiled .swf?