Using values from a slider

I have a slider and a plot which automatically updates as I move the slider however depending on where I place the sliders I would like the values to create a subset of my dataset. I am confused regarding hwo the sliders work and how to go about this. I thought that I simply needed to use n2 =

value1 = get(slider1,'Value');
value2 = get(slider2,'value');
at the end of my function and then 
simply create a new data = Olddata(Value1:Value2).

However, I get errors which say that Value1 and Value2 are undefined. How does this work because I have nested functions does it mean that every time I move my slider this new subset needs to be updated. How can I do this?

function sliderattempt
global Datasetnew
MM = load('Datasetold.txt');
X = MM(:,2);
f = figure('Visible','off');
hAxes = axes('Position',[.1 .15 .8 .8]);
sldplot=plot(X);
x_limit = get(gca,'XLim');
y_limit = get(gca,'YLim');
n = numel(X);
s1 = uicontrol('Style', 'slider','Min',1,'Max',n,'Value',1,'Position', [100 5 120 20],'Callback', @s1_Callback);
s2 = uicontrol('Style', 'slider','Min',1,'Max',n,'Value',n,'Position', [400 5 120 20],'Callback', @s2_Callback);
txt = uicontrol('Style','text','Position',[400 30 120 15],'String','Second');
txt2 = uicontrol('Style','text','Position',[100 30 120 15],'String','First');
addlistener(s1, 'ContinuousValueChange', @S1ListenerCallback);
addlistener(s2, 'ContinuousValueChange', @S2ListenerCallback);
set(f,'Visible','on');
      function S1ListenerCallback(source,callbackdata)
          n2 = round(get(s1,'Value'));
          n3 = round(get(s2, 'Value'));
          set(sldplot,'xdata',(n2:n3),'ydata',X(n2:n3));
          set(gca,'XLim',x_limit,'YLim',y_limit)
          drawnow;
      end
      function s1_Callback(source,callbackdata)
          n2 = round(get(s1,'Value'));
          n3 = round(get(s2, 'Value'));
          set(sldplot,'xdata',(n2:n3),'ydata',X(n2:n3));
          set(gca,'XLim',x_limit,'YLim',y_limit)
          drawnow;
      end
      function S2ListenerCallback(source,callbackdata)
          n2 = round(get(s1,'Value'));
          n3 = round(get(s2, 'Value'));
          set(sldplot,'xdata',(n2:n3),'ydata',X(n2:n3));
          set(gca,'XLim',x_limit,'YLim',y_limit)
          drawnow;
      end
      function s2_Callback(source,callbackdata)
          n2 = round(get(s1,'Value'));
          n3 = round(get(s2, 'Value'));
          set(sldplot,'xdata',(n2:n3),'ydata',X(n2:n3));
          set(gca,'XLim',x_limit,'YLim',y_limit)
          drawnow;
      end
  Datasetnew = Datasetold(n2:n3);
end