Error "Unable to resolve the name gurobi.Model."

Hello,

I'm using Gurobi to solve the problem of min-cost flow on graphs with radiality contraints. Here is the code that I'm using :

n = 4;
R = [1];

% Define the isconnected function
isconnected = @(G) numel(unique(conncomp(G))) == 1;

% Set the connectivity ratio of the graph
p = 1;

% Generate a random adjacency matrix
AA = triu(rand(n) < p, 1);
AA = AA + AA';

% Create a connected graph from the adjacency matrix
while ~isconnected(graph(AA))
    AA = triu(rand(n) < p, 1);
    AA = AA + AA';
end
S = AA;

for i = 1:n
    for j = 1:n
        if ismember(i, R) == 1
            S(n, i) = 1;
            S(i, n) = 1;
        else
            S(n, i) = 0;
            S(i, n) = 0;
        end
    end
end
G = graph(S);
p=plot(G);


% Define other problem data (cost vector c, constraint rho, etc.)
% (Replace these with the actual data)
c = ones(n, n); % Cost vector c (n x n matrix)
for i=1:n-1
     rho_in(i)=0;
end

rho_in(n)=n-1-length(R);


for i=1:n-1
    if ismember(i,R)==0
    rho_fin(i)=1;
    else
        rho_fin(i)=0;
    end
        
    %input(sprintf('rho_fin(%d)=',i));
end
rho_fin(n)=0;
RHO=(rho_in-rho_fin)';

  
try
    % Create Gurobi model
    model = gurobi.Model();

    % Add variables b_{i,j} and x_{i,j}
    b = model.addVars(n, n, 'B'); % Binary variables
    x = model.addVars(n, n, 'C'); % Continuous variables

    % Set objective function
    obj = 0;
    for i = 1:n
        for j = 1:n
            if S(i, j) == 1
                obj = obj + c(i, j) * b(i, j) * x(i, j);
            end
        end
    end
    model.setObjective(obj, 'minimize');

    % Add constraints
    % Constraint: \sum_{j\in N(i)} b_{i,j}x_{i,j} - \sum_{j\in N(i)} b_{j,i}x_{j,i} = \rho(i) for all i
    for i = 1:n
        expr = 0;
        for j = 1:n
            if S(i, j) == 1
                expr = expr + b(i, j) * x(i, j) - b(j, i) * x(j, i);
            end
        end
        model.addConstr(expr == RHO(i));
    end

    % Additional Radiality Constraints
    for j = 1:n
        if ~ismember(j, R) % If j is not in the set R (set of sources)
            model.addConstr(sum(b(:, j)) == 1);
        end
        for i = 1:n
            if S(i, j) == 1
                model.addConstr(b(i, j) + b(j, i) <= 1);
            end
            if ismember(j, R) % If j is in the set R (set of sources)
                model.addConstr(b(i, j) == 0);
            end
        end
    end

    % Optimize the model
    model.optimize();

    % Display the solution
    disp('Objective value:');
    disp(model.objval);
    disp('Binary variables b:');
    disp(model.getAttr('x', b));
    disp('Continuous variables x:');
    disp(model.getAttr('x', x));

catch gurobiError
    disp('Error reported by Gurobi');
    disp(gurobiError.message);
end

I get always this error message: Error reported by Gurobi
Unable to resolve the name gurobi.Model.

I want to know please what is exactly the probleml?. Thank you.