Snapnow is not working in compiled code

I have created a GUI in which need to capture the image and display it in the GUI. I need to display grid and grid axis around the image so was using snapnow to do it. The script runs without any errors in matlab, but when i compile it into a standalone application it is giving error on snapnow command.

I have compiled it as command line application and this is the error what i am getting:

Undefined function or variable 'snapnow'.
Error in CVC_b2>Btn_Captr_Img_Callback (line 278)
Error in gui_mainfcn (line 96)
Error in CVC_b2 (line 51)
Error in
@(hObject,eventdata)CVC_b2('Btn_Captr_Img_Callback',hObject,eventdata,guidata(hObject))
Error while evaluating uicontrol Callback

[Vishal]

Hey !!

Got the problem resolved by using

drawnow

instead of

snapnow

but i am still not sure why snapnow is not working as both are publishing the images. Can someone please help me understand what is the difference b/w the two commands and how come drawnow worked where snapnow threw error.