Why does trainNetwork return an error? - Error using trainNetwork (line 184) Layers argument must be an array of layers or a layer graph.

Why does trainNetwork not recognise my layers?

I've tried copy-pasting prebuilt layers from a .mlx tutorial but i'm receiving the same error regardless, even when I turn it into an lgraph,

can anyone explain why this error is occuring...here is my full code,

thanks,

%[xTrain, yTrain, xValidation, yValidation, augTrain, augValid] = trainingDataGetter(1);

load("augTrain.mat");

load("augValid.mat");

load("yTrain.mat");

load("yValid.mat");

layers = [...

imageInputLayer([24 24 3])

convolution3dLayer([12 12 3],8,'Padding',1)

fullyConnectedLayer(1)

regressionLayer

]

lgraph = layerGraph(layers);

miniBatchSize = 128;

validationFrequency = floor(numel(augTrain.Files)/miniBatchSize);

options = trainingOptions('sgdm', ...

'MiniBatchSize',miniBatchSize, ...

'MaxEpochs',30, ...

'InitialLearnRate',1e-3, ...

'LearnRateSchedule','piecewise', ...

'LearnRateDropFactor',0.1, ...

'LearnRateDropPeriod',20, ...

'Shuffle','every-epoch', ...

'ValidationData',{augValid,yValidation}, ...

'ValidationFrequency',validationFrequency, ...

'Plots','training-progress', ...

'Verbose',false);

net = trainNetwork(augTrain,yTrain,layers,options);