Finite Element method (FEM) for fft and alanyze it

can you please look at this code, I am not sure what is wrong with the code,

clear all;colordef white;clf

% materials

E = 10e7; poisson = 0.30;

% matriz C

C=E/(1-poisson^2)*[1 poisson 0;poisson 1 0;0 0 (1-poisson)/2];

% load

P = 1e6;

%Mesh generation

Lx=5;

Ly=1;

numberElementsX=20;

numberElementsY=10;

numberElements=numberElementsX*numberElementsY;

[nodeCoordinates, elementNodes] = ...

rectangularMesh(Lx,Ly,numberElementsX,numberElementsY);

xx=nodeCoordinates(:,1);

yy=nodeCoordinates(:,2);

drawingMesh(nodeCoordinates,elementNodes,'Q4','k-');

numberNodes=size(xx,1);

% GDof: global number of degrees of freedom

GDof=2*numberNodes;