Why do I get this error?

Hi,

I am using this code to select an area from an image on an axes using the mouse.

r = imrect; % choose the area by drawing a rectangle
fcn = makeConstrainToRectFcn('imrect',get(ax1,'XLim'),get(ax1,'YLim'));
setPositionConstraintFcn(r,fcn);
setResizable(r,false);
rectangle_position = getPosition(r);
rectangle_position = uint8(rectangle_position);

It works but I am getting this error at the end:

"Expected one output from a curly brace or dot indexing expression, but there were 0 results.

Error in imroi/setPositionConstraintFcn (line 210)

obj.api.setPositionConstraintFcn(fcn);

Error in select_area (line 10)

r.setPositionConstraintFcn(fcn);"

Can someone help me please?