Simulink Mask initialization command and RuntimeObject

Here is code for my mask initialization I want to use it to change the color according to outputs of one of the blocks

    systems = find_system(gcb,'LookUnderMasks' , 'on', 'FollowLinks','on', 'SearchDepth', 1,'regexp','on','Name','Multi');
    rto=get_param(systems{1,1},'RuntimeObject')
    if rto.OutputPort(1).Data == 1
        set_param(gcb,'BackgroundColor','red')
    else
        set_param(gcb,'BackgroundColor','green')
    end

When I press OK I get `Error: Dot indexing is not supported for variables of this type`

When I use `keyboard` to debug I get this

    K>> rto
    
    rto =
    
    	handle

It seems that it can't get the runtimeobject but when I do this while still in debug mode

 rto=get_param(systems{1,1},'RuntimeObject');

while debugging I did get it

  rto =
    
    	Simulink.RunTimeBlock