You have to many typos and incomplete sentences for this to make and sense

I would listen the manufacturer... :-)
I use these tests and I follow instructions and compare colors
holding sample vial over WHITE background. To get WHITE background
you CANNOT put the vial right at the color scale because your
will cause the white ambient light go through the color vial
once, then hit the white background coloring it, and go back toward
your eyes. In effect you are watching at the test tube placed on
the already colored background with the color light shining through it.

I keep the vial slightly elevated from the background, the way
the white piece of the scale is lighted with WHITE light...

If you put the vial right on the scale you should be reading
double concentrations to what is real, if you know what I mean.

I always get readings between the colors and I can never tell what I
truly have. Is there a better way to test the levels in my tank? Also
what the correct way to measure the colors against the cards.

To cure this problem, ask what color does your sister/wife/girlfriend
see - women have much better developed color recognition skills than men
do.