Sorry, that one won't do. It's you who have to prove the Soviet Union was not provinding goods at the quantities contracted, not the others who have to prove they did. If you raise an accusation the onus of proving it is yours.
Does it matter? It was an Axis principle that any country refusing to sell it's oil to an Axis state was committing an "act of war" and deserved to be invaded and have it's natural resources exploited for the good of the Axis. Hitler never signed a treaty he didn't eventually violate.