Why the results of Elman network were different every time I run the codes?

I created a elman network. But the results every time I run the code were different.I got different "errors","regression" and "avg_error" Could anyone tell me why? Appreciate SO MUCH! Here is the code.

clear all

load('input4_train.mat');

load('output4_train.mat');

load('input4_test.mat');

load('output4_test.mat');

inputSeries = tonndata(input4_train,false,false);

targetSeries = tonndata(output4_train,false,false);

inputTest = tonndata(input4_test,false,false);

outputTest = tonndata(output4_test,false,false);

% Create a Network

hiddenLayerSize = 5;

net=newelm(inputSeries,targetSeries,[10,3,1], {'tansig','logsig','purelin'});

% Setup Division of Data for Training, Validation, Testing

net.divideParam.trainRatio = 70/100;

net.divideParam.valRatio = 15/100;

net.divideParam.testRatio = 15/100;

net.trainParam.epochs = 2000;

% Initial net

net = init(net);

% Train the Network

net = adapt(net,inputSeries,targetSeries);

% Test the Network

outputs = sim(net,inputTest);

errors = gsubtract(outputTest,outputs);

error = cell2mat(errors);

for i = 1:10

    error(i)=abs(error(i));

end

avg_error = sum(error)/10;

performance = perform(net,outputTest,outputs);

% View the Network

view(net)

% Plots

figure, plotregression(outputTest,outputs)

figure, plotresponse(outputTest,outputs)

figure, ploterrcorr(errors)

[Walter Roberson]

duplicates http://uk.mathworks.com/matlabcentral/answers/231949-why-the-results-of-my-elman-network-are-different-every-time