fsolve works only if I run the code once

Hi everyone! I get this error message and I thought I might have forgotten a * sign, but apparently it isn't so. What could be wrong?

Main:

% fsolve caller
aaaa=fsolve(@(Z) base_montante(Z,vet_1_base_montante,vet_2_base_montante),-ex_1);

function with vector of equations:

function F = base_montante(Z,vet_1_base_montante,vet_2_base_montante)

vet_3_base_montante=zeros(3,1);

ex_1=[1;
      0;
      0];

vet_3_base_montante(1)=Z(1);
vet_3_base_montante(2)=Z(2);
vet_3_base_montante(3)=Z(3);

F=[dot(vet_3_base_montante,vet_1_base_montante);
   dot(vet_3_base_montante,vet_2_base_montante); 
   dot(vet_3_base_montante,-ex_1)-1];

vet_1_base_montante , ex, and vet_2_base_montante are pre-assigned vectors, so it should solve for the 3 components of vet_3_base_montante...

Here's the complete error message, though only the first line should be the cause for it all:

Subscript indices must either be real positive integers or logicals.

Error in @(Z)base_montante(Z,vet_1_base_montante,vet_2_base_montante)

Error in fsolve (line 219)
            fuser = feval(funfcn{3},x,varargin{:});

Caused by:
    Failure in initial user-supplied objective function evaluation. FSOLVE cannot continue.

If I type "clear all" and run the code again, I get no error message and the results make sense. If I run it again, I get the same error I reported. By typing

dbstop if error

the debugger brings me to the "fsolve" code, and apparently there's a problem with the Jacobian, as what makes the code stop is at line 224 (little green arrow). But I don't know what that's about...

[Stephen23]

duplicate:

https://www.mathworks.com/matlabcentral/answers/333385-subscript-indices-must-either-be-real-positive-integers-or-logicals-fsolve-problem