NON LINEAR PDE ERROR IN SIMULINK

I TRY TO SIMULATE A NON-LINEAR MODEL IN SIMULINK WITH MATLAB FUNCTION, insert my equations but I got a zero result when including my discretization, why is it?

BLOQUE01

function D = fcn(theta)

L=10; %comprimento

z=linspace(0,L,5); % espaco de discretizacao

theta_r = 0.218; % conteudo de agua residual

alpha= 0.0115; %parametro de Van Genuchten 1/cm (Van Genuchten, 1980)

K_s = 31.6; % conductividade de saturacao cm/t

theta_s=0.52; %conteudo de agua saturado

n = 2.03;

m=1-(1/n);

i=2:length(z);

D =(K_s*(1-m)/(alpha*m*(theta_s-theta_r)))*(theta(i-1).^(0.5-(1/m))./(1-(theta(i-1).^(1/m)))).*((1-(1-(theta(i-1).^(1/m))).^m).^2);

bloque 02

function K = fcn(theta)

L=10; %comprimento

z=linspace(0,L,5); % espaco de discretizacao

theta_r = 0.218; % conteudo de agua residual

alpha= 0.0115; %parametro de Van Genuchten 1/cm (Van Genuchten, 1980)

K_s = 31.6; % conductividade de saturacao cm/t

theta_s=0.52; %conteudo de agua saturado

%dz=L/length(z);

%b=1/(2*dz);

n = 2.03;

m=1-(1/n);

i=2:length(z);

K = K_s*(theta(i-1).^(1/2)).*(( 1-(1-(theta(i-1).^(1/m))).^m).^2);

bloque 03

function dot_theta = Richards(theta,D,K)

L=10; %comprimento

z=linspace(0,L,5); % espaco de discretizacao

dz=L/length(z);

b=1/(2*dz^2);

i=2:length(z),

k=i-1,

j=i-2,

dot_theta=b*(D(j+1)+D(k)).*(theta(j+1)-theta(k))- b*(D(i-1)+D(k)).*(theta(k)-theta(i-1))+((K(k)-K(i-1))/dz);