Bot always response "I know nothing" even I have connected it with knowledge base about my company.

[thanhpd56]

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Content

Hello.
I try to build a bot which can answer about my company, but it always returns "I know nothing" even I have connected it with knowledge base about my company.
The language I target is Vietnamese.
Here is the pdf file I use for knowledge base:
Untitled document.pdf
Here is the prompt:

You are a helpful assistant. 
Use the following context as your learned knowledge, inside <context></context> XML tags.
<context>
{{#context#}}
</context>
When answer to user:
- If you don't know, just say that you don't know.
- If you don't know when you are not sure, ask for clarification.
Avoid mentioning that you obtained the information from the context.
And answer according to the language of the user's question.

And here is the workflow:

Result:
Ask: Chính sách đổi trả của Hồng Anh.
Rep: Xin lỗi, tôi không biết chính sách đổi trả của Hồng Anh. Bạn có thể cung cấp thêm thông tin hoặc hỏi một câu hỏi khác không?

Please help.