How can I change the color of a country using a shapefile?

Hello all,

I have downloaded a shapefile including all countries from the Natural Earth website: http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/50m/cultural/ne_50m_admin_0_countries.zip

I first read the shapefile:

%%Load country borders shapefile
country_border_file = 'shapefiles\ne_50m_admin_0_countries\ne_50m_admin_0_countries.shp';
country_borders = shaperead(country_border_file,'UseGeoCoords',true);

and then plot it using the geoshow function:

ax = axesm('mercator');
geoshow(ax, [country_borders.Lat], [country_borders.Lon], 'Color', 'k');

Everything works fine for this. Now, I would like to colour Germany and UK land areas a specific colour to improve map visibility. I run the following code:

ax = axesm('mercator');
symspec = makesymbolspec('Polygon', ...
                         {'name', 'Germany', 'FaceColor', [0.15 0.5 0.15]}, ...
                         {'name', 'United Kingdom', 'FaceColor', [0.15 0.5 0.15]});
geoshow(ax,country_borders,'SymbolSpec', symspec)

And I get the following error messages:

*??? Error using ==> line Invalid property found. Object Name : line Property Name : 'SymbolSpec'.

Error in ==> mapline at 24 h = line(xdata(:), ydata(:), 'Color', [0 0 1], varargin{:});

Error in ==> geovec at 22 h = fcn(x, y, varargin{:});

Error in ==> geovecshow at 66 h = geovec(mstruct, lat, lon, ...

Error in ==> geoshow at 273 h = showFcn(varargin{:});*

Generally, I am not able to do anything beyond plot the lines. Facecolor and other arguments do not work either giving similar error messages.

My question is: Is there a way around this problem (and if not) is there a freely-available shapefile (I have tested many other with similar problems) that has been tested to work well with MATLAB (i.e. country-specific colour painting works)?

Thank you very much in advance, Ioannis