Translation:I drink milk and I do not drink juice.
Curious, in Russian there are two ands, а and и. Where one shows contrast... is there only one in Ukrainian, like in English? In Russian, the а would go here, not the и.
In Russian а would not go there. It would be «Я пью молоко и не пью сок», «Он любит спать и не любит работать»(Він любить спати і не любить працювати) and so on.
Ukrainian has «а», which is not used here for the same reason as in Russian, I suspect. We treat such sentences more like an enumeration of preferences rather than a statement of contrast.
However, you can say «Я п'ю молоко, а сік не п'ю» (I hope I got it right). This word order makes the emphasis seem natural. When not reversed, it is rather weird ("...and as for not drinking, juice is the thing I do not drink")
"а" is also possible in a sentence like this: Я п’ю молоко, а не сік (what I drink is milk and not juice)
One possible thing is that you entered a Latin "i" instead of the Cyrillic "і" or "a" instead of "а". Unfortunately, they are not the same UTF characters and are not interchangeable.
"і" is the only correct answer here.