Bad information looks just like good information
No information is always better than bad information. When you don't know the answer, say so and go find out.
The problem with bad information is that it looks just like good information, which makes it very dangerous.
If you’re not sure, don’t guess, assume, pretend or lie – just tell them you don’t know and when you’ll bring the answer. They can organise themselves while they wait for the answer to come.
There is no shame in not knowing, but lying is a sign of incompetence or disengagement and neither will get you very far.