Why do I get the same output from Predict function in LSTM?

Hi everyone.

I have input matrix with 8 feature and 1000 samples.I want to predict price with this matrix. I train LSTM with input matrix and test LSTM with Predict function. I test trained LSTM 10 times with predict function,But I get the same output from Predict function every time.How cal I solve this problem? here is may code:

function LSTM_net(data,dataTest,filename,range,date,varargin)

%--------------80% of data for train and 20% for validation----------------

out_day=cell.empty;

index=size(data{1,1},1)*0.8;

findex=round(index,0);

dataTrain=data(1:findex,:);

dataval=data(findex+1:end,:);

%-----------------Normalization of training/validation data----------------

dataTrain(isnan(dataTrain))=0;

dataval(isnan(dataval))=0;

dataTrain=rescale(dataTrain,0,1);

dataval=rescale(dataval,0,1);

YTrain = dataTrain(:,end)';

XTrain = dataTrain(:,1:end-1)';

XTrain = num2cell(XTrain,1);

YTrain = num2cell(YTrain,1);

yval= dataval(:,end)';

xval = dataval(:,1:end-1)';

xval = num2cell(xval,1);

yval = num2cell(yval,1);

%-----------------------Define Network Architecture------------------------

numResponses = size(YTrain{1},1);

featureDimension = size(XTrain{1},1);

numHiddenUnits = 15;

layers = [ ...

sequenceInputLayer(featureDimension)

lstmLayer(numHiddenUnits,'OutputMode','sequence')

dropoutLayer(0.5) %%0.5

fullyConnectedLayer(numResponses)

regressionLayer];

maxepochs = 500;

options = trainingOptions('sgdm', ...

'MaxEpochs',maxepochs, ...

'InitialLearnRate',0.01, ...

'L2Regularization',0.001,...

'ValidationData',{xval,yval},...

'ValidationPatience',5,...

'ValidationFrequency',10);

%---------------------------------set test data----------------------------

dataTest=rescale(dataTest,0,1);

YTest = dataTest{k,1}(:,end)';

XTest = dataTest{k,1}(:,1:end-1)';

XTest = num2cell(XTest,1);

YTest = num2cell(YTest,1);

%---------------------------------Train the Network------------------------

out_net=single.empty;

%load('net_checkpoint__110__2021_11_01__10_49_03_555','net');

[net1,info] = trainNetwork(XTrain,YTrain,layers,options);

for i=1:10

YPred = predict(net1,XTest);

net1 = resetState(net1);

%figure;

%subplot(2,1,1);

y1 = (cell2mat(YPred(1:end, 1:end)));

%plot(y1);

%title('Forcasted');

%subplot(2,1,2);

y2 = (cell2mat(YTest(1:end, 1:end))');

%plot(y2);

%title('Observed');

y1(isnan(y1))=0;

y2(isnan(y2))=0;

%----------------------------calculate MAE,RMSE,MAPE-----------------------

out_net(i,1)=mean(info.TrainingRMSE(1,:),2);

out_net(i,2)=mean(abs(y1-y2)); %MAE

out_net(i,3)=mean(abs((y1-y2)/mean(y1))); %MAPE

out_net(i,4) = sqrt(mean((y1-y2).^2)); %RMSE

if size(varargin,1)==1 %for plot regression

predict_y(:,i)=y1;

end

end

end

I trained LSTM one time and predict it for 10 times and I get the same YPred answer every time.Is my code true?Please help me.