I am using the assitants api but it gives me a problem

My question is the following: I have a development where my clients can use a chat section and this chat is linked to chatgpt, this chat has the function of assistants but on some occasions when clients ask a question and the chat tells me that the answer It is not found in the documents that the attendees have but then in another chat the same question is asked again and it gives me the correct answer.

I attach images with the examples.
Imagen 1

Imagen 2
image

Why this error occurs ?

Hi!
If you are sure that the information is indeed inside the files used for retrieval then there are two options. Either the model did really not find it or it did not even try to find it. You can learn about the steps of the run to identify which problem is arising in your case.
https://platform.openai.com/docs/api-reference/runs/listRunSteps

In both cases you would likely have to adjust your prompt to make it really clear to the model when to reference the knowledge files and, even better, which part of it.