How do I get the name of the signal if it is not in a structured array?

I am attempting to set the parameter of a bus selector to a specific signal in a masked sub system using

load_system('simulink');
set_param(gcb, 'MaskSelfModifiable', 'on');
ph = get_param([gcb,'/In1'],'PortHandles');
sh = get_param(ph.Outport, 'SignalHierarchy');
sc = sh.Children(sns,1).SignalName;
set_param([gcb,'/Bus'],'OutputSignals',sc);

sns is a user input to the masked block

The code above alters the contents of the masked subsytem by when I go to simulate the model I recieve 2 errors

Initialization commands cannot be evaluated.

and

Attempt to reference field of non-structure array.

How do I get the name of the signal if it is not in a structured array?

[Kaustubha Govind]

What do you get in sh when you run the same commands in the MATLAB prompt after selecting the subsystem?