Looking on the internet deeply has found these results:

it should not happen is the most popular phrase on the web.

it should not be happened 117,000 results on the web	it should not happen 123,100 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
What happened was just something that happened. Whatever happened, it must have happened quickly. Whatever happened to these power lines happened after the snow monster. Maybe what happened to our two victims also happened to his mother. Work happened later, marriage happened later, kids happened later, even death happened later. What happened to Charlie happened because... What happened to him could've happened to any qualified pilot. What happened last night has never happened.	nomising: LightingEurope says that halogens ... Thiruma About Modi! nakkheeranwebtv. Subscribe SubscribedUnsubscribe 30,745. Subscription preferences. Loading. Jan 28, 2015 ... Health Blog. Recurrence of measles and why it should not happen. Jane Sadler Email drjane65@gmail.com. Published: January 28, 2015 2:26 ... Apr 3, 2015 ... Undertaker vs Sting: Why it should NOT happen. Controversial Radio. Subscribe SubscribedUnsubscribe 31 ... Dec 28, 2013 ... It Should Not Happen Jan 21, 2015 ... The halogen ban: Why it should not happen. The halogen ban: Why it should not happen. Eco

it should not be happened

117,000 results on the web

it should not happen

123,100 results on the web

More popular!

What happened was just something that happened.
Whatever happened, it must have happened quickly.
Whatever happened to these power lines happened after the snow monster.
Maybe what happened to our two victims also happened to his mother.
Work happened later, marriage happened later, kids happened later, even death happened later.
What happened to Charlie happened because...
What happened to him could've happened to any qualified pilot.
What happened last night has never happened.

nomising: LightingEurope says that halogens ...
Thiruma About Modi! nakkheeranwebtv. Subscribe SubscribedUnsubscribe 30,745. Subscription preferences. Loading.
Jan 28, 2015 ... Health Blog. Recurrence of measles and why it should not happen. Jane Sadler Email drjane65@gmail.com. Published: January 28, 2015 2:26 ...
Apr 3, 2015 ... Undertaker vs Sting: Why it should NOT happen. Controversial Radio. Subscribe SubscribedUnsubscribe 31 ...
Dec 28, 2013 ... It Should Not Happen
Jan 21, 2015 ... The halogen ban: Why it should not happen. The halogen ban: Why it should not happen. Eco