[GUI] How do I open and run a simulation previously created in simulink?

Hello all, I've created a model of a bouncing ball using simulink, I've run the simulation and the model is working, now I've created a GUI where I want to open and run this simulation, heres the GUI: http://prntscr.com/crphoh

This is the code I've used to open the simulation model:

[filename, pathname] = uigetfile({'*.slx;*', 'Pick a .slx file'});

This is the code I've used to run the simulation:

modelname = get(handles.modelname, 'String');
stoptime = str2num(get(handles.simstoptime, 'String'));
sim(modelname, [0 stoptime])

And finally the code I used to stop the simulation: global GUIStopFlag; GUIStopFlag = 1;

So, none of those above work, I can't open the simulation model or run it, I get nothing on the GUI. Any help?

[Preethi]

remove ; from

[filename, pathname] = uigetfile({'*.slx;*', 'Pick a .slx file'});

is the screenshot of GUI attached complete?