Modal verbs

[engee30]

Both are okay.
"You must have a permit to enter the national park." -- necessity

If someone other than you tells you what you're supposed to do, must is fine and means a direct order:
Ranger: 'You must have a permit to enter the national park.'

If you think that you should do something, then must means a strong self-persuasion:
I must see that new movie by Spielberg. They say it's marvellous.

When talking about someone else's orders or things that are necessary for you to do, you use have to:
The ranger told me that we had to have a permit to enter the park.
Do you know if we have to have visas for the Caribbean?

[Raymott]

The job interview was a disaster; i could only answer half the questions.

What is happening here? Native speakers are giving correct and appropriate usage advice to learners, and non-native speakers are not only contradicting them, but giving "authoritative" statements of what one can and can't say in English, based on a web-page. You're not dealing with semi-literate dolts here, Svartnik.
David, Chris, Engee and I have all said that this sentence is good, correct, grammatical English.
Perhaps you need to put your mouse aside; speak to some native speakers and learn a little humility and respect.

[swedish meatball]

What is happening here? Native speakers are giving correct and appropriate usage advice to learners, and non-native speakers are not only contradicting them, but giving "authoritative" statements of what one can and can't say in English, based on a web-page. You're not dealing with semi-literate dolts here, Svartnik.
David, Chris, Engee and I have all said that this sentence is good, correct, grammatical English.
Perhaps you need to put your mouse aside; speak to some native speakers and learn a little humility and respect.

As a native english speaker (and a teacher with many years experience), I completely agree with the above. The sentence in question to me sounded perfectly acceptable.
Try not to bite the hand that feeds you Svartnik!