Error with my custom components

Seasoned AS3 developer, but not very experienced with the CS4 environment.
I could use some help here, if anyone knowledgeable could spare the time.

Here is my situation:
I have an actionscript base class, which declares
public class ASBaseClass extends UIMovieClip {
public var Image_Holder : UIMovieClip;

}

I also have 2 library elements:
ASLibraryElement (baseclass ASBaseClass)
GenericUIMovieClip (baseclass UIMovieClip)

Now… on the timeline of ASLibraryElement, I am attempting to instantiate this property by placing a GenericUIMovieClip instance named Image_Holder onto the timeline for ASLibraryElement

The problem is when I attempt to compile, I’m getting an 1152: Conflict exists with inherited definition in public namespace for Image_Holder

From what I understand, this should be possible to do what I’m trying to do.
Anyone care to shed some light on the subject?

Additional information:
Library properties declare export to actionscript, export to frame 1
I used FCK on this to convert to flex component
File settings are exporting to a swc, and does NOT automatically declare stage instances.

Thanks!