MFnMatrixAttribute not showing up in attr editor (Python API)

[shredder]

Hey guys, I am trying to add a matrix attribute to a custom python node that will show up in the attribute editor. I have done this same type of thing in a C++ plugin, but for some reason the attr doesnt show up when made in python.

@classmethod
    def nodeInitializer(cls):
 
        mAttr = om.MFnMatrixAttribute()
        nAttr = om.MFnNumericAttribute()
 
        cls.objectMatrixAttr = mAttr.create(cls.omLongName, cls.omShortName, om.MFnMatrixAttribute.kDouble)
        mAttr.setKeyable(True)
        mAttr.setReadable(True)
        mAttr.setWritable(True)
        mAttr.setChannelBox(True)
        mAttr.setStorable(True)        cls.addAttribute(cls.objectMatrixAttr)

I make a node and there is no errors. I look at it in the attr editor and there is no matrix there.
If I go to the connection editor, it is there, and I can connect things to it. but I can not get it to show up in the editor.

I started with just setKeyable in there.. like it is in C++, and added all the others to try to get it to show up, to no avail.

Anyone have any ideas??

thanks!

[shredder]

as a side note, the addAttr is on the next line in the code..