present tense - Why aren't these sentences correct?

​Hello everyone! I have a very easy question. Why aren't these sentences correct?

-I haven't received an answer (on my mobile phone) for more than a week.

-This offence is called XxXxXx and occurs when you comment on a thread that hasn't received an answer for more than a week.

I'm using Present Perfect with the duration form: "for a week" but I found out they're not correct and I personally can't understand why.