Need help integrating Gemini API key



"Please help me check if this Web API block diagram is correct? When I hadn’t attached “candidates” → “content” → “parts” → “text” and only attached the response to set label câu trả lời text to for testing, it returned the following JSON structure: { “candidates”: [ { “content”: { “parts”: [ { “text”: "Here’s something interesting about the universe:
Most of the universe is missing!
Not in a “lost keys” kind of way, but in a "we can’t directly "

But when I connected all the blocks “candidates” → “content” → “parts” → “text” to set label câu trả lời text to, the result returned null. I don’t know where I made a mistake. Could you please point out the error and guide me on how to fix it so that the Gemini Web API can work?
Thank you very much!