Where is the mistake?

Have you been to Scotland?
Yes, I’ve been there last year.

Where is the mistake in these two lines?

Can please somebody help me with this?

Please can somebody help me with this?

Have you been to Scotland?
Yes, I went there last year.

You need to change the tense in the answer because of the time phrase, which clearly indicates it was a visit at a specific time in the past.

Compare it with:
Have you been to Scotland?
Yes, I’ve been there a few times. (no specific past time mentioned0

Hi,

can I not say “Yes, I had been there last year”?

Not as a direct answer to the question ‘Have you been to Scotland?’

Have you been to Scotland,
Yes, I went there last year.

Had you been to Scotland previously?
Yes, I had been there the previous year.

If the question is “Had you been to Scotland?”,

Can the answer be “Yes, I had been there last year”?

The direct answer to your question would have to be ‘yes’, BUT that question (tense) would not be asked without an additional phrase.

Had you been to Scotland before your last visit?
Had you been to Scotland in the past?
Had you been to Scotland previously?
Had you been to Scotland before you got married?

So can I ask “Had you been to Scotland last year?”

No. ‘Last year’ is not enough of a qualifying phrase.

Thank you for clarifying my doubt!

You’re welcome, Sarkpri.

I’ve just noticed you’re a new member - welcome to the forums!