Plotting data for COVID-19 case

Could you help me know what problem is in this code? I'm trying to show one plot by App Designer. Without App Designer, below code is working to make a plot. Could you let me know how I could make a plot by using the attached file? Thank you!

   properties (Access = private)
        TimePoints 
        Raw_Data % Data for only case & death
        Case
        Death

    end

    methods (Access = private)
        function startupFcn(app)
load covid_data.mat data;
app.Raw_Data = cell2mat(covid_data(2:end,3:end));
Temp = covid_data(1,3:end);
app.TimePoints = datetime(Temp);
app.Case = sum(app.Raw_Data(:,1:2:end));
app.Death = sum(app.Raw_Data(:,2:2:end));
yyaxis(app.UIAxes,"left");
plot(app.UIAxes,app.TimePoints,app.Case);
yyaxis(app.UIAxes,"right");
plot(app.UIAxes,app.TimePoints,app.Death);
        end