How do I show VARIABLE image file in Matlab app designer?

function testagiletahminButtonPushed(app, event)
             load testag4.mat % Önceen eğitilen ağı yüklüyoruz.
             [TestAdi, TestYolu] = uigetfile ('*.png','Test Resmi Seçiniz');
            A=imread([TestYolu, TestAdi]);
             app.Image.ImageSource=imshow(A) % ONLY THIS ONE IS FAULTY! EVERYTHING ELSE WORKS!
              %IT DOESN'T ACCEPT THE CODE ABOVE! A IS THE INPUT "IMAGE" SELECTED BY
            %THE USER. WHAT MUST THE CODE BE LIKE? 

How do we fix this? It says:

Error using matlab.ui.control.Image/set.ImageSource (line 123)
ImageSource value must be a valid file path, or an m-by-n-by-3 color data matrix.

[Sampath Rachumallu]

Try this app.Image.ImageSource=A;