i have Error using edge Expected input number 1, I, to be one of these types:

citra = handles.image;
tresH = 0.1;
citraGray = rgb2gray(citra);
citraSobel = edge('citraGray', tresH,  'sobel');
axes(handles.axes2);
imshow(citraSobel);

[darova]

Try without apostrophe

citraSobel = edge(citraGray, tresH,  'sobel');