about x date tick.

I used version is

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MATLAB Version: 8.0.0.783 (R2012b)
MATLAB License Number: ••••••
Operating System: Linux 2.6.32-431.el6.x86_64 #1 SMP Fri Nov 22 03:15:09 UTC 2013 x86_64
Java Version: Java 1.7.0_55-b13 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
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I draw plot I used datenum and datetick

I attach my plot. this plot x tick is no match.

for example Tidal Wavelet Power Spectrum plot(4,1,1) "12/19 00" is originally "12/20 00".

what's the problem?

----------------------my program--------------------------------------------------------

     %saveext='.png'
    filepath='./34_tide_01.dat'
    [path,name,ext] =fileparts(filepath)

    %x=load('yg_2005_12.txt');
    dat=load(filepath);

    dox=19 % start julian day
    doy=dox+3 %end day

    date_v=datenum(dat(:,1), dat(:,2), dat(:,3), dat(:,4), dat(:,5), dat(:,6))

    %datetick('x','mm/dd hh')

    x=dat(:,11);
    num=size(x);

    for i = 1:num(1)
        if x(i) < 0
         x(i)= NaN;
        end
    end

    %Tide interpolation

    for i = 1:num(1)
        if isnan(x(i)) ==1
            if i-5 <= 0
               % x(i)=nanmean(x(i:i+5));
                angle=nanmean(x(i:i+5));
               if isnan(x(i+1)) ==0
                inter=x(i+1)-angle*(i+1)
               elseif isnan(x(i+2)) ==0
                inter=x(i+2)-angle*(i+2)
               elseif isnan(x(i+3)) ==0
                inter=x(i+3)-angle*(i+3)
               elseif isnan(x(i+4)) ==0
                inter=x(i+4)-angle*(i+4)
               elseif isnan(x(i+5)) ==0
                inter=x(i+5)-angle*(i+5)
               end
            elseif i+5 >= num(1)

                x(i)=nanmean(x(i-5:i));

            else
               x(i)=nanmean(x(i-5:i+5));
            end
        end
    end

    %date(:,11)=interp1(date(:,11),1,)
    %x=dat(:,11);

    %------------------------------------------high pass filter
    hour=1
    Fs=1.0/60.0; %fampling frequency
    Fs=1
    n=9; %order
    %Wn=1/(3600*12+60*25) %cut off frequency 10Hz
    Wn=1/(hour*3600);
    Wn=1/60
    Fn=Fs/2; %Nyquist frequency
    ftype='high' %bandpass or low or high
    [b,a]=butter(n,Wn/Fn,ftype);

    y=filter(b,a,x);

    %tide return NaN
    for i = 1:num(1)
        if isnan(x(i)) ==1
            if i-5 <= 0
                y(i:i+5)=0;
                x(i:i+5)=NaN
            elseif i+5 >= num(1)

                y(i-5:i)=0;
                x(i-5:i)=NaN

            else
               y(i-5:i+5)=0;
               x(i-5:i+5)=NaN
            end
        end
    end

    x=x(dox*1440:doy*1440)
    y=y(dox*1440:doy*1440)
    date_v=date_v(dox*1440:doy*1440)
    num=size(x);

    %-----------------------------------wavelet transform

    %sst=y(dox*1440:doy*1440)
    sst=y;

    variance = std(sst)^2;
    sst = (sst - mean(sst))/sqrt(variance) ;

    n = length(sst);
    %dt = 0.25 ;
    dt = 1
    time = date_v  ;  % construct time array
    %xlim = [1,1440];  % plotting range
    pad = 1;      % pad the time series with zeroes (recommended)
    %dj = 0.25;    % this will do 4 sub-octaves per octave
    dj = 0.25
    s0 = 2*dt;    % this says start at a scale of 6 months
    j1 = 5/dj;    % this says do 7 powers-of-two with dj sub-octaves each
    lag1 = 0.72;  % lag-1 autocorrelation for red noise background
    mother = 'Morlet';

    % Wavelet transform:
    [wave,period,scale,coi] = wavelet(sst,dt,pad,dj,s0,j1,mother);
    power = (abs(wave)).^2 ;        % compute wavelet power spectrum

    % Significance levels: (variance=1 for the normalized SST)
    [signif,fft_theor] = wave_signif(1.0,dt,scale,0,lag1,-1,-1,mother);
    sig95 = (signif')*(ones(1,n));  % expand signif --> (J+1)x(N) array
    sig95 = power ./ sig95;         % where ratio > 1, power is significant

    % Global wavelet spectrum & significance levels:
    global_ws = variance*(sum(power')/n);   % time-average over all times
    dof = n - scale;  % the -scale corrects for padding at edges
    global_signif = wave_signif(variance,dt,scale,1,lag1,-1,dof,mother);

    % Scale-average between El Nino periods of 2--8 years
    avg = find((scale >= 2) & (scale < 8));
    Cdelta = 0.776;   % this is for the MORLET wavelet
    scale_avg = (scale')*(ones(1,n));  % expand scale --> (J+1)x(N) array
    scale_avg = power ./ scale_avg;   % [Eqn(24)]
    scale_avg = variance*dj*dt/Cdelta*sum(scale_avg(avg,:));   % [Eqn(24)]
    scaleavg_signif = wave_signif(variance,dt,scale,2,lag1,-1,[2,7.9],mother);

    whos

    levels = [4,8,16,32,64,128,256] ;
    Yticks = 2.^(fix(log2(min(period))):fix(log2(max(period))));

    %contour(time,log2(period),log2(power),log2(levels));  %*** or use 'contourfill'
    %contour(time,log2(period),log2(power),log2(levels))

    %subplot('position',[0.1 0.75 0.65 0.2])
    subplot(4,1,1)
    %imagesc(time,log2(period),log2(power));  %*** uncomment for 'image' plot

    imagesc(time,log2(period),log2(power),'CDataMapping','scaled')
    colormap(jet)

    %contour(time,log2(period),log2(power),'CDataMapping','scaled')
    %contourf(time,log2(period),log2(power),'CDataMapping','scaled')
    %caxis([0,])

    %set(gca,'XMinorTick','on','XMinorGrid','on')

    xlabel('Time(KST)')

    datetick('x','mm/dd hh')

    set(gca,'XLim',[time(1),time(num(1))])
    set(gca,'XTick',[time(1):0.125:time(num(1))])

    grid on

    ylabel('Period (min)')
    title('Tidal Wavelet Power Spectrum')

    set(gca,'YLim',log2([min(period),max(period)]), ...
        'YDir','reverse', ...
        'YTick',log2(Yticks(:)), ...
        'YTickLabel',Yticks)

    % 95% significance contour, levels at -99 (fake) and 1 (95% signidatf)
    hold on
    contour(time,log2(period),sig95,[-99,1],'k');
    hold on
    % cone-of-influence, anything "below" is dubious
    plot(time,log2(coi),'k')
    hold off

    %num=size(time)
    for i = 1:num(1)
        powerserise(i) = max(power(:,i));
    end

    subplot(4,1,2)
    plot(date_v,powerserise)
    datetick('x','mm/dd hh')
    set(gca,'XLim',[date_v(1),date_v(num(1))])

    subplot(4,1,3)
    %plot(y(dox*1440:doy*1440))
    plot(date_v,y)
    datetick('x','mm/dd hh')
    set(gca,'XLim',[date_v(1),date_v(num(1))])

    subplot(4,1,4)
    %plot(x(dox*1440:doy*1440))
    plot(date_v,x)
    datetick('x','mm/dd hh')
    set(gca,'XLim',[date_v(1),date_v(num(1))])