Hi Ali, I had a simlar problem, see my mesage about 3 up to Nick. I set an expression to check that there was an answer from the Knowledge base and if not I sent it off to answer the question with I have no anser for that then carried on For my no answer I used an AI task so I got a personality if using the personality I think that just putting a text answer would work. in the Knowledge agent I told it specifically this. "Response must contain significant results otherwise give no answer." and in the AI tasks for no response I put this: "If the topic is not within the provided data answer "I am sorry but I don't have an answer for that." Worked for me. As a note I did this in the cloud UI so not yet tried with the API learning that part at the moment.