ModuleNotFoundError: No module named 'langchain' is occured

[diqksk]

even I installed langchain but error is occured

File "D:\ML\test\Llama-2-Open-Source-LLM-CPU-Inference\main.py", line 3, in
from src.utils import setup_dbqa
File "D:\ML\test\Llama-2-Open-Source-LLM-CPU-Inference\src\utils.py", line 7, in
from langchain import PromptTemplate
ModuleNotFoundError: No module named 'langchain

I used keyword "pip install -r requirements.txt" and install them all.

how should I do?