References undefined while autocomplete does find the reference

Question

When I add references to my file it outputs a question mark and the error message "citation 'label' in page '1' undefined." However, autocomplete does notice the reference which implies to me the path to the reference and the reference itself are correct. Am I missing something obvious? I added a minimal working example of my latex code below, which I edited in VSCode. Any suggesting are appreciated, thank you.

\documentclass{article}
\usepackage[nottoc]{tocbibind}
\begin{document}
Whenever i cite a citation \cite{KOEL1} it shows up in autocomplete.
However, the cite command is still outputting errors and question marks.
the error is :
LaTeX Warning: Citation `KJRATPROB' on page 1 undefined on input line 52.
\bibliographystyle{plain}
\bibliography{reference}
\end{document}

Edit solution: This was a bibtex problem which was solved by running biber "document name" in the terminal. It also helped to change my imports to: \usepackage[backend=biber]{biblatex} \addbibresource{reference.bib}