To add insult to injury means to make a bad situation worse, and in this sentence the last twenty-four hours have made a bad situation even worse by not coming up with anything conclusive.
Context: To make things worse, the last twenty-four hours have not come up with anything conclusive
Hypothesis: To add insult to injury, the last twenty four hours have not come up with anything conclusive.

Is the hypothesis incorrect? (Yes, no, or unknown)?