Hi Methos,
first of all, are you building a component or an extension? only
non-visible components are supported as extensions, unless you are
using a hack that has recently been discussed in this list and works
in certain cases.
If it is a component, the you don't need to 'ant extensions' and then
'ant'. 'ant' would suffice, but you will need to use the new version
of the companion that is built during process and that includes the
new component you created. The stock companion will not contain it and
will fail with an error similar to the one you reported.
If this is an extension, then it should work with the stock companion,
but then I am not sure if you are writing the correct code for a
visible component which is not allowed as an extension (except for
that hack mentioned).
This is what needs to be done with the Companion if you are working on
a Component (not an extension):
https://docs.google.com/document/u/1/pub?id=1Xc9yt02x3BRoq5m1PJHBr81OOv69rEBy8LVG_84j9jc#h.3aibbept75tt
Hope that helps!
cheers,
José