I was building a Connect 4 game in C, but when I try to add alpha-beta pruning to the minimax algorithm it simply doesn’t work, can anyone explain why? This is a part of my code:

void bestMove(int totalMoves) { // AI's turn
  int score, move;
  float bestScore = -INFINITY;

  depth = 5+totalMoves*0.15;

  for(int c = 0; c < COLUMNS; c++) {
    for(int r = 0; r < ROWS; r++) {
      if(board[r][c] == 0 && board[r+1][c] != 0 || board[r][c] == 0 && r == ROWS - 1) { // Is the spot available
        board[r][c] = AI_PLAYER;
        score = minimax(depth, false);
        board[r][c] = 0;
        if(score > bestScore) {
            bestScore = score;
            engineEvaluation = bestScore;
            move = c;
        }
      }
    }
  }
  uptadeBoard(AI_PLAYER, move);
}

int minimax(int depth, bool isMaximazing) { // Minimax algorithm implementation
    int scores[3] = {0, -1000000, 1000000}, result, score;
    float bestScore;
    nodes++;
    result = checkWinner();
    if(result != 3) {
        return scores[result];
    }

    if(isMaximazing) {
        bestScore = -INFINITY;
        for(int c = 0; c < COLUMNS; c++) {
            for(int r = 0; r < ROWS; r++) {
                if(board[r][c] == 0 && board[r+1][c] != 0 || board[r][c] == 0 && r == ROWS - 1) { // Is the spot available
                    board[r][c] = AI_PLAYER;
                        if(depth > 0) {
                            score = minimax(depth-1, false);
                        } else {
                            score = evaluation();
                        }
                    board[r][c] = 0;
                    bestScore = max(score, bestScore);
                    alpha = bestScore;
                    if(alpha >= beta) {
                        break;
                    }
                }
            }
        }
        return bestScore;
    } else {
        bestScore = INFINITY;
        for(int c = 0; c < COLUMNS; c++) {
            for(int r = 0; r < ROWS; r++) {
                if(board[r][c] == 0 && board[r+1][c] != 0 || board[r][c] == 0 && r == ROWS - 1) { // Is the spot available
                    board[r][c] = HUMAN_PLAYER;
                        if(depth > 0) {
                            score = minimax(depth-1, true);
                        } else {
                            score = evaluation();
                        }
                    board[r][c] = 0;
                    bestScore = min(score, bestScore);
                    beta = bestScore;
                    if(alpha > beta) {
                        break;
                    }
                }
            }
        }
        return bestScore;
    }
}

For some reason my program just ignore the alpha-beta implementation, if anyone want the full code it’s here: https://github.com/MatheuSs-GIT/Connect-4-Game-in-C/tree/main, thanks!