how do I use LOS2?

I'm trying to see if there is line of sight between an aircraft (UA) and a satellite (I5) using LOS. I used the following script:

      clear all;
        close all;

        %satellite coordiantes
        I5_lat = 0;
        I5_long = 62.2;
        I5_alt = 35786000; %m
        effectiveradius = 4/3*earthRadius;
        actualradius = earthRadius;

        %Aircraft Coordinates
        UA_lat = 88;
        UA_long = -5;
        UA_alt = 0;

        %region of interest
        lat=54:0.1:89.5;
        long = -17.1:0.1:43.3;
        latlim = [54 89.5];
        lonlim = [-17.1 43.3];

        layers = wmsfind('nasa.network*elev', 'SearchField', 'serverurl');
        layers = wmsupdate(layers);

        aster = layers.refine('earthaster', 'SearchField', 'layername');
        cellSize = dms2degrees([0,6,0]);

        %obtain elevation data for region of interest
        [ZA, RA] = wmsread(aster, 'Latlim', latlim, 'Lonlim', lonlim, ...
           'CellSize', cellSize, 'ImageFormat', 'image/bil');

        %determine if there is Line of sight
        vis = los2(double(ZA),RA,UA_lat,UA_long,I5_lat,I5_long,UA_alt,I5_alt,'MSL', ... 
          'MSL',earthRadius,4/3*earthRadius)

I don't expect there to be line of sight between the aircraft and the satellite when the aircraft is at lat=88deg N and long = 5 deg west, but the LOS2 function returns a '1'. Can you what is wrong with the script?

Thanks, Keihan