Including all values of subgroup in Gchart/VAR3D

[k9rescue]

I've got a character field named Butterflies.  I've got a numeric field named Test.  Test values are 1-6.   I'm trying to create a vbar where all the Test values are represented, even if there is no data for them.   This will make the graphic colors across all charts the same.  I tried the code below, but it's ignoring the midpoints do not match the variable type.  Any idea what's going on?

PROC GCHART DATA=mydata

;

  VBAR3D

  Butterflies

/

  SUBGROUP=Test

/* Start of custom user code. */

patternid = subgroup

/* End of custom user code. */

  SHAPE=BLOCK

FRAME TYPE=FREQ

  MISSING

PCT

  LEGEND=LEGEND1

  COUTLINE=BLACK

  RAXIS=AXIS1

  MAXIS=AXIS2

/* Start of custom user code. */

discrete

midpoints=1 2 3 4 5 6;

[ballardw]

When I have a similar need I usually join the data to a data set with all of the categorical variables. If the value isn't in the data set then GCHART can't do anything with it.