Astronomers have been unable to prove it exists?

Astronomers are unable to prove the existence of dark matter & dark energy.

In fact astronomers have not yet proved most astronomical effects. Worm holes, black holes, or even the big bang. But proof in theories is almost impossible. The longer a theory stays intact is a sign of it's "proof" but some "sane" theories have been proven to be incorrect - "Einsteins biggest blunder".

No scientist will say they have proved anything "astronomical" as it is almost impossible to prove anything without physical interaction.

It's a bit like saying "I can prove that dogs live in the next street" based on only hearing their barks and not actually going there.