"that" – could be replaced with "this", "something", "it". But "that" is a pronoun here. So it (if they accept "that" as a synonym). Wait, maybe "it" or "the matter". Hmm.
Given the ambiguity, proceed with the initial thought, even if grammatical issues might arise, as long as the synonyms are valid alternatives.
can't → Not able (but need to check if these are correct synonyms)