rosserial custom message compilation problems

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I have updated rosserial to 0.3.0, and as far as I can tell also updated everything else along with it. I have a custom message defined and now my rosserial_arduino sketch won't compile.

The compiler was complaining about my message being an abstract type so I added const to the end of the serialize function definition.

When I use make_library.py to recompile the message it has an error about Header. I get "roslib.msgs.MsgSpecException: sensor_state.msg: Header header is not a legal message type"

I'd appreciate a pointer in the right direction please.