[AccessD] A2003: Plot a Vertical Line on a fuel gauge

Hi Team
I am trying to get the syntax right to plot a vertical line on a horizontal
"fuel gauge"
Fuel gauge looks something like |___|___|___|___|

Fuel gauge is made up of 5 vertical lines representing (from L to R)
Empty(Minimum), 1/4, 1/2, 3/4, and Full (Maximum)
With a long line underneath the 5 vertical lines representing the plane

User enters 3 values into controls on a form
1 = MIN
2 = MAX
3 = Desired (Is always going to fall somewhere between min and max - handled
by data entry rules)

The 1st and 2nd values entered indicate what the max and min are to be IE
Empty and Full
EG Min = 100,000
Eg Max = 300,000
EG "Desired" = 200,000

So I should see (Using the above example) the vertical line indicating
"Desired" sit above the Half Full vertical line
But so far I am doing something wrong - 'cause when I enter 1 as a min 3 as
a max and 2 as desired the vertical line plots perfectly

But when I use 100 as min 300 as max and 200 as "desired" I get a slight
shift of the "Desired" vertical line to the right
And it increases (I think exponetially) as I increase the Min and Max by
increments of say...thousands

So...Any tips on the logic I should use?

Anyone wanna see the demo - lemme know

Many thanks in advance

Darren