Error while evaulating uicontrol Callback. Troubles using slider uicontrol

Hey all,

I have a bunch of data which I would like to plot versus time. Because this data was taken over the course of three hours I'd like to add a slider to my plots in order to better view the data. The plots are 2,1 subplots and I'd like the slider to move both plots simultaneously so data can be compared. My problem is that when I run the code, some plots work fine, and some don't. I can't find the error anywhere! I just constantly get this message when trying to move some:

??? Error while evaluating uicontrol Callback

??? Error using ==> set Bad property value found. Object Name : uicontrol Property Name : 'XLimInclude'.

OR

??? Error while evaluating uicontrol Callback

??? Error using ==> set Invalid handle object.

THINGS I'VE NOTICED: When I run the code multiple times, it's always the same plots which don't work. If I plot a different number of plots (only columns 1-10 of data on different plots instead of 1-20) some plots will still not work BUT not the same plots. I.E. By changing the bounds I can get a plot which previously didn't work to work. I'm lost! I'll add my code below: I tried to remove as much non-essential stuff as possible.

CODE:

%% miscellaneous definitions

close all

clear all

clc

format long;

dateformat='HH:MM:SS.FFF';

%% Load the correct data

[filename, pathname] =uigetfile({'*.*';'*.csv*';'*.xls*'; '*.xlsx*';'*.CO2*'}, 'Which data would you like to work with?', 'C:\Users\Sean E\Documents\APSF', 'MultiSelect', 'off'); LoadData(filename, pathname);

%%

for i=4:22

        figure(i-3); %create figure

        eval(strcat('h',num2str((i-3)*2-1),'=subplot(2,1,1);')); %subplot
        plot(C{1,1}(1:end),C{1,i}(1:end)); %plot (time array) vs (data array)

        title(headernames(1,i)); % graph formatting
        xlabel('Time'); % graph formatting
        ylim([min(C{1,i})-.05*min(C{1,i}), max(C{1,i})+.05*max(C{1,i})]); 
        set(gca,'XTick',newtimesmat); % graph formatting
        set(gca,'XTickLabel',times); % graph formatting

        eval(strcat('h',num2str((i-tstart+1)*2),'=subplot(2,1,2);')) %create subplot
        plot(C{1,1}(1:end),C{1,18}(1:end)); %plot (time array) vs (reference data)

        title(headernames(1,18)); % graph formatting
        xlabel('Time'); % graph formatting
        ylim([min(C{1,18})-.05*min(C{1,18}), max(C{1,18})+.05*max(C{1,18})]); 
        set(gca,'XTick',newtimesmat); % graph formatting
        set(gca,'XTickLabel',times); % graph formatting

        dx=0.002083333325572; %defining constants
        x=newtimesmat; %defining constants
        eval(strcat('varargin={h' ,num2str((i-tstart+1)*2-1),',h',num2str((i-... 
        ...tstart+1)*2),'};'));
        a=gca; %defining constants
        set(a,'xlim',[0 dx]); %defining constants
        pos=get(a,'position'); %defining constants
        xmax=max(x); %defining constants
        xmin=min(x); %defining constants
        Newpos=[pos(1) pos(2)-0.1 pos(3) 0.05]; %defining constants

        for k = 1:length(varargin);
            %initialize postion of plot
            set(varargin{k},'xlim',[xmin xmin+dx]);
            % Creation of variables b1...bn
            eval(['b',num2str(k+(i-tstart+1)+(i-tstart-1)), ' = varargin{k};'])
            % Setting up callback string to modify XLim of axis (gca)
            % based on the position of the slider (gcbo) 
            if k == 1;
                    S=['set(b', num2str(k+(i-tstart+1)+(i-tstart-1)), '... 
                         ...,''xlim'',get(gcbo,''value'')+[0 ' num2str(dx) ']);'];
                else
                    S=[S ', set(b', num2str(k+(i-tstart+1)+(i-tstart-1)), ' ...
                        ...,''xlim'',get(gcbo,''value'')+[0 ' num2str(dx) ']);'];
                end
        end
        % Creating Uicontrol with initial value of the minimum of x
        eval(strcat('b',num2str(i),'=uicontrol(''style'',''slider'',''units'',''normalized'',...
        ...''position'',Newpos,''callback'',S,''min'',xmin,''max'',xmax-dx,''value'',xmin);'));
end