Error when building the Mex Function using Matlab Coder: " The size to the left is the size of the left-hand side of the assignment."

I'm using Matlab Coder in Matlab-r2014b and I have the following problem. I'm reporting here a sample code with structure and type of variables similar to my real one.

1) The script that calls the entry-point

    clear all
    N=3 ;              
    Res=alg(N);

2) The entry-point

    function val=alg(N)

    coder.varsize('matrixfinal');
    matrixfinal=zeros(1,3*N+2); 

    profindex=randi(N+1,2^(N-1),1);

    for s=1:10

    coder.varsize('matrix');
    matrix=zeros(1,3*N+2);

    for k=1:2^(N-1)
        if profindex(k)==N-1
           matrix=[matrix; randi(1,1,3*N+2)];
        end
    end

    if size(matrix,1)>1
       matrix(1,:)=[];
    end

    for k=1:size(matrix,1)
        count=0;
        for h=1:size(matrixfinal,1)
            if sum(matrix(k,2+2*N:3*N)==matrixfinal(h,2+2*N:3*N))==N-1
               count=1;
               matrixfinal(h,3*N+1)=matrixfinal(h,3*N+1)+matrix(k,3*N+1);
               matrixfinal(h,3*N+2)=matrixfinal(h,3*N+2)+matrix(k,3*N+2);
            end        
        end
        if count==0
            matrixfinal=[matrixfinal; matrix(k,:)];
        end
    end

    end

    if size(matrixfinal,1)>1
       matrixfinal(1,:)=[];
    end

    val=matrixfinal(1,1); 

    end

When I try to built the Mex Function I get the following error

    ??? Size mismatch (size [1 x :?] ~= size [2 x :?]).
    The size to the left is the size of the left-hand side of the assignment.

    Error in ==> alg Line: 29 Column: 9

The line of the error is `matrixfinal=[matrixfinal; matrix(k,:)];`

How can I solve this problem? All the code lines are strictly necessary and cannot be changed.