I've got a head-scratcher here.
We're updating an older Flex 3 project (3.6 SDK) and have (mostly) succussfully migrated the project to FB4.5 but we're sticking with the 3.6 SDK.
One particular element of this project is a masthead which we publish as a .swc from Flash 5.5 after using the "Convert Symbol to Flex Component" command. I've also written a simple class for this masthead component so we can get at some interal properties.
The .swc isn't visible at all. It's there, I've confirmed that using the debugger but it won't display. I've even tried pulling it into a bare-bones project file using both the old 3.6 SDK and the 4.5 SDK. Nothing.
Maybe I'm follow an old workflow for bringing Flash elements into Flash Builder?
I noticed there are two Flex Component kits, but I'm pretty sure Flash 5.5 already has the Flex Component kit built-in. Yes?
You mentioned that this was a project you migrated over to FB 4.6,
correct? Chances are that even though you have the swc in your lib
folder, the project properties are pointing to a version of the swc in a
Choose Project > Properties > Flex Build Path >Library Path and then
click the swc that's having problems, click "Edit" on the right, and
confirm that it's pointing to the correct location.
Finally figured out that my co-worker had changed the class and extended MovieClip rather than UIMovieClip. All is well again. =)