fsolve return same values for various inputs

I have a system of 8 equation and 8 unknown

with function

function G=Gt(a,P,Po,H2CO,GCH4,GH2O,GCO,GCO2,GH2,GC,T)
% number of element C H and O : 3
% aik i denoted species and k is elemnt
R=8.314467e-3; %kj-kg-k
a_CH4_C=1; a_CH4_H=4;a_CH4_O=0;
a_H2O_C=0; a_H2O_H=2;a_H2O_O=1;
a_CO_C=1; a_CO_H=0; a_CO_O=1;
a_CO2_C=1; a_CO2_H=0; a_CO2_O=2;
a_H2_C=0; a_H2_H=2;a_H2_O=0;
a_C_C=1; a_C_H=0; a_C_O=0;
% A_k  k is elemnt in the mixture for example C
% A_C=a_CH4_C*noCH4+a_CO_C*noCO+a_CO2_C*noCO2+a_C_C*noC;
% A_H=a_CH4_H*noCH4+a_H2O_H*noH2O+a_H2_H*noH2;
% A_O=a_H2O_O*noH2O+a_CO_O*noCO+a_CO2_O*noCO2;
% a(1)=ych4 a(2)=yh2o a(3)=yco a(4)=yco2 a(5)=yh2 a(6)=yc
% ther are three lagrange multuolier: Gama_c (a(7), Gama_h a(8) and Gama_o
% a(9)
NCH4=a(1)^2;
NH2O=a(2)^2;
NCO=a(3)^2;
NCO2=a(4)^2;
NH2=a(5)^2;
NC=a(6)^2;
Gc=a(7)^2;
GH=a(8)^2;
GO=a(9)^2;

nt=NCH4+NH2O+NCO+NCO2+NH2+NC;
G(1)=NCH4+nt*exp(-(GCH4/(R*T)+a_CH4_C*Gc/(R*T)+a_CH4_H*GH/(R*T)));  %CH4
G(2)=NH2O+nt*exp(-(GH2O/(R*T)+a_H2O_H*GH/(R*T)+a_H2O_O*GO/(R*T)));  %H2O
G(3)=NCO+nt*exp(-(GCO/(R*T)+a_CO_C*Gc/(R*T)+a_CO_O*GO/(R*T)));    %CO
G(4)=NCO2+nt*exp(-(GCO2/(R*T)+a_CO2_C*Gc/(R*T)+a_CO2_O*GO/(R*T)));    %CO2
G(5)=NH2+nt*exp(-(GH2/(R*T)+a_H2_H*GH/(R*T)));    %H2
G(6)=NC+nt*exp(-(GC/(R*T)+a_C_C*Gc/(R*T)));    %H2
G(7)= a_CH4_C*NCH4+a_CO2_C*NCO2+a_CO_C*NCO+a_C_C*NC-1;
G(8)= a_CH4_H*NCH4+a_H2O_H*NH2O+a_H2_H*NH2-H2CO*2;
G(9)= a_H2O_O*NH2O+a_CO_O*NCO+a_CO2_O*NCO2-1;
% G(9)= NCH4+NH2O+NCO+NCO2+NH2+NC-1;

end

a0=[0.626 0.228 0.408 0.0375 0.268 0.91 1000 2400 100];

i recieved this answers:

Iteration Func-count f(x) step optimality

0 10 3.03569 4.96

1 20 3.03569 0.982623 4.96

2 30 1.42864 0.245656 1.67

3 40 0.539709 0.491311 0.351

4 50 0.461848 0.199711 0.095

5 60 0.459377 0.0498161 0.00399

6 70 0.459364 0.00484322 7.79e-05

7 80 0.459364 4.80893e-05 2.34e-06

8 90 0.459364 2.62314e-06 1.12e-07

9 100 0.459364 9.64716e-08 4.51e-09

10 110 0.459364 4.58492e-09 3.8e-09

No solution found.

fsolve stopped because the last step was ineffective. However, the vector of function

values is not near zero, as measured by the selected value of the function tolerance.

<stopping criteria details>

[Walter Roberson]

To test, we will need to know the values you are passing in for H2CO, GCH4, GH2O, GCO, GCO2, GH2 ,GC, T .

(You do not use P or Po so we can ignore those.)