>>>>Well, is that user a DB owner of that particular user DB (that user who you're using to log into SQL Server)?
>>>
>>>Yes.
>>
>>In your connection string do you specify the DB?
>
>You were right. Such a stupid error on my part, wrong DB name (it is long and I missed one letter). Thank you!

You're welcome. I got a similar problem recently when I made a typo which was not really visible. Took me several hours to notice it.