How to define a classification model from workspace in a GUIDE app ?

I'm going to classify an new image data set with my GUIDE app and a SVM classification model which I created using the classification learner toolbox. I already export the model into a variable in workspace named 'trainedClassifier'. But when I use

yfit = trainedClassifier.predictFcn(T);

in my program. I get 'Undefined variable "trainedClassifier" or class "trainedClassifier.predictFcn".' error. Is there any way to define a variable which already in the workspace inside my program ? I already try to save the classification model into a .mat file and load the file in my program but when I call

yfit = trainedClassifier.predictFcn(T);

I get 'Reference to non-existent field 'predictFcn'.' error. Any help will be appreciated thanks.