Because you didn't lodge a signed vote. I think the abstain votes are from directors, who have a vested interest in the outcome, so are compelled to abstain by the company articles of association (the governing rules of a company).
I.e. if you don't vote, just like in the federal elections and much more specifically the council elections you can - go fish. (in the council ones they'd be lucky to get 30% of the public voting).
IMVHO.
PS. I'm presuming you're a young person like my son, just trying to find out how these things work.
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