Screen size in multiplot mode of Gnuplot

I have 5 sub-plots, and only four of them are showing. The code snippets are as follows, since the original code is quite long; I am not able to increase the screen size to accomodate the 5th plot, and as a result, only the first four shows up:

set output 'test.png'
set size 1.75,1.75
set terminal png font "/Library/Fonts/Times New Roman Bold.ttf, 10" size 1000,700   
set origin 0,0
set multiplot

#1st
set size 0.5,0.5
set origin 0,0.5
...
#2nd
set size 0.5,0.5
set origin 0,0
...
#3rd
set size 0.5,0.5
set origin 0.5,0
..开发者_开发技巧.
#4th
set size 0.5,0.5
set origin 0.5,0.5
...
#5th, and this one is not showing up
set size 0.5,0.5
set origin 1,0.5
...

Where am I going wrong?

You are setting the origin of the fifth plot to 1, 0.5. This lets gnuplot plot it outside of the window.
Try this arrangement:

set size 1, 0.2

#first plot
set origin 0, 0.8
plot ...

#second plot
set origin 0, 0.6
plot ...

#third plot
set origin 0, 0.4
plot ...

#fourth plot
set origin 0, 0.2
plot ...

#fifth plot
set origin 0, 0.0
plot ...

I haven't tested the above but I hope you get the idea behind it.
Maybe the documentation about multiplot is also helpful.