I have zero result Why?

Typical reasons

1. A massive s-channel particle has a width set to zero.
2. The pdf are zero for at least one of the initial state particles.
3. The cuts are too strong.
4. For decay computation the mass of the final state is larger than the mass of the initial state.

Please take a look at your Cards (param_card/ run_card)

More particular reason

In presence of 4 point interactions and if you have diagram with 3 point interaction but that the coupling are such that all 3 point interaction are zero, MG can fail to integrate the 4 point interactions. We advice you to use a restricted model whithout those superfluous 3 point interactions and MG will integrate correctly the 4 point interaction diagram.