Sometimes, you can make it work.
The AI will respond "I don't see how we can make this work", if it believes that a fair deal cannot be made. If the reason for this is that he values his trade offering more than anything you have, then you cannot change it.
However, if you are offering something more valuable than everything the AI owns, like a major city, he may say "I don't see how we can make this work", but then agree to an alternative offer that is unfair to YOU. He will not agree to an offer unfair to him.
Changing the trade offering on either side can still result in a workable trade after the AI has made that assessment.