Passing Data from child app back to parent app.

Hello. I am trying to pass data from from a child app that is called from within my main app.

My main app is H_TestSoftware.mapp.

In this app there is a pushbutton (PlotManipButtonPushed) that calls a 2nd app (my child app) and passes in an axes and table from the main app.

PlotManipButtonPushed(app, event)
    ax1=app.UIAxes3
    ex=app.UITable.  
    PlotAnalysis(ax1, ex);     % My Child App   

In the startup code of my child app (PlotAnalysis.mapp), I have this:

function startupFcn(app, ax, ex)
    app.sourceAxes = ax;      % Keep reference to original axes
    app.out=ex;               % Original parent table I want to pass data back to

where sourceAxes and out are defined in the child app properties

properties (Access = public)
    sourceAxes  % Keep reference to your original axes   
    out         % used tor eturn data back to calling APP

So in my child app(PlotAnalysis), I have a push button which collects data from a uitable in the (child) app and then I thought I can assign it to the out property (as its linked to the uitable in parent app) and it will then populate the calling apps uitable - but it doesn't

 function TestButtonPushed(app, event)
    % Get Data from Table (in child app)
    T=app.UITable;
    data=T.Data;
    % send back to calling app's table
    app.out.Data=data;

Unable to perform assignment because dot indexing is not supported for variables of this type.
Error in PlotAnalysis/TestButtonPushed (line 1434)
            app.out.Data=data;

1: Any suggestions to what Im doing wrong please.

2: Another question, is it possible to use some functions defined in my main app in the child app so I don't have to recreate them in it.

thanks

Jason