I need help in code ENSO

Hi

I run this code but at final i recive in output NaN data?

the sstj.nc

clear
clc
sst = ncread('sstj.nc','sst');tt = double(ncread('sstj.nc','time'));
lats1 = double(ncread('sstj.nc','latitude'));lons1 = double(ncread('sstj.nc','longitude'));
[Lat,Lon] = meshgrid(lats1,lons1);
idx1 = enso(sst,tt,Lat,Lon);
idx2 = amo(sst,tt,Lat,Lon);
figure(1)
anomaly(tt,idx1,'thresh',[-0.4 0.4]);
axis tight
hline(0,'k') % places a horizontal line at 0
datetick('x','keeplimits')
ylabel 'Nino 3.4 SST anomaly (\circC)'
figure(2)
plot(tt,idx2)
ylabel 'AMO index'

what's the problem i attach data and code

best

Mahboub