I got an error in my script using fsolve command

My error is:

Objective function is returning undefined values at initial point. FSOLVE cannot continue.

QR=1000;
T1=20;
T2=T1;
TM=50;
Ks=0.5;
L=0.10;
h1=20;
h2=h1;
hm=10;
R1=1/h1;
R2=1/hm;
R3=1/hm;
R5=1/h2;

%Funciones

F= @(x) [(T1-x(1))/R1+(TM-x(1))/R2+QR;
        (x(1)-TM)/R2+(x(2)-TM)/R3;
        (TM-x(2))/R3+Ks*(x(3)-x(2))/x(4);
        Ks*(x(2)-x(3))/x(4)+(T2-x(3))/R5];

x0=[0,0,0,0];
sol=fsolve(F,x0,options);
R=[sol(1) sol(2) sol(3)];

I don´t know where is the error at :(

[Alex Sha]

Hi, Jaime, are the results below you want?

x1: 63.3333333333333
x2: 36.6666666666667
x3: 26.6666666666667
x4: 0.0375

Answer 1

[Matt J]

>> F(x0)

ans =

        1900
       -1000
         NaN
         NaN