Is your module enabled ? Have you update the function name according to your module name ? Have you got some image style ? Otherwise put some dpm() function or put some xdebug breakpoint at each steps to see where and why the code don't generate the image style.
Is your module enabled ? Have you update the function name according to your module name ? Have you got some image style ? Otherwise put some dpm() function or put some xdebug breakpoint at each steps to see where and why the code don't generate the image style.