How do I score contract bonus points?

This one has me stumped, how do I score bonus contract points as the demo? (Gunmettle)
The instructions were to kill enemies while performing the objective, or something to that effect. I was pushing the cart on Borneo and killed enemies while defending it, and got no bonus.
What exactly am I doing wrong? I tried both melee and grenades, but still nothing.
Best Answer
It's likely bugged on Payload maps. I recommend trying it on a KOTH map like koth_suijin.
Edit: If it wasn't clear, you can only do contracts on Valve servers. No other servers counts. The easiest way to find Valve servers is using the Play Now button (or whatever the QuickPlay button is called now... top button in the default HUD, making sure your search settings are set to "Official servers").
Note: Bonus Points can be scored on ANY Valve server, not just GunMettle.
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How do you keep score in Contract Bridge?
Points for each trick required and taken are scored as follows: 20 points in clubs and diamonds, 30 points in hearts and spades, 40 points for trick 7 in notrump and 30 points per trick over trick 7. These points are multiplied by two or quadrupled respectively if the contract has been doubled or redoubled.How do you score points in duplicate bridge?
Your aim is to bid and make a game. This scores a bonus of 300 points (or 500 if vulnerable). If you bid a contract that scores less than 100 points, this is called a Part Score. If you make a Part Score you score a bonus of 50 points.How are points calculated in bridge?
A bridge hand contains thirteen cards. Each ace in the hand is worth four points, each king is worth three points, each queen two points, and each jack one. The other cards, twos through tens, have no point value. So if your hand has two aces, a king, two jacks, and eight other cards, it's worth thirteen points.What is the score for 3NT in bridge?
3NT is worth 50 + 10 + 3 \ufffd 30 = 150 points as a partscore, so 3NT doubled is 2 \ufffd 150 + 250 = 550! Note that the more silly the opponents' double, the more points you get. For example, 2 doubled making 4 is worth 670, but 4 doubled making 4 is only worth 590.Scoring in Bridge - Bonus Points
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