Immovable Asteroid

[Wilds]

I just docked my asteroid mover to a 35 million ton asteroid. It has 6 nervs and 4 darts. I cannot move the asteroid one bit. I have about a 0.004 TWR if I do rough math. Game reports 0.00 TWR.

I assumed it is immovable. But for testing, a Mammoth will produce 0.02 TWR at max power. I cheated a craft to the asteroid with a Mammoth. The Mammoth could move the asteroid.

Here's my problem: The Mammoth can still move the asteroid producing just 60 kN of thrust at around 1% thrust. My asteroid mover vessel produces way more than that, but its max TWR is below 0.00. What can I do to move the asteroid using my craft?